Content is not the same as a Member. So you have to return a MemberDisplay

 EditorModelEventManager.SendingMemberModel += this.EditorModelEventManager_SendingMemberModel;

 private void EditorModelEventManager_SendingMemberModel(System.Web.Http.Filters.HttpActionExecutedContext sender, EditorModelEventArgs<Umbraco.Web.Models.ContentEditing.MemberDisplay> e)
    {
    }

But then i can't find really a option to disable it maybe you have some ideas @dave

Thanks Dave but as Julien pointed out, unfortunately, the MemberDisplay class does not have an AllowedActions property like ContentItemDisplay

Interesting, I will take a look into that. Thanks

Morning David, I've made good progress on this now and have it working without the check on userGroup so thanks for your help. My angular skills are far from an expert and I am struggling to get access to userService so I can perform the userGroup check. What is the correct way to gain access to the service here?

If I do the following I get a circular dependency error:

angular.module('umbraco').factory('memberSaveButtonInterceptor', ['$q', 'userService', memberSaveButtonInterceptor]);
angular.module('umbraco').config(['$httpProvider', addInterceptors]);

Circular dependency: authResource <- userService <- memberSaveButtonInterceptor <- $http <- umbRequestHelper <- mediaHelper

Sure, here you go.

(() => {

    // This could be done using content events, but that then means the injected directive would need to be compiled
    // while this is a bit flaky, it ensures the directive is in the DOM when the digest cycle runs so should be more efficient
    // passing the prefix in to the directive allows construction of correct class names
    // Ref: https://github.com/nathanwoulfe/NestingContently/blob/master/src/NestingContently/backoffice/interceptor.js
    function memberSaveButtonInterceptor($q, userService) {
        return {
            response: resp => {
                if (resp.config.url.toLowerCase().indexOf('views/member/edit.html') !== -1) {
                    const pattern = /<umb-button[\s\S]*? type="submit"[\s\S]*? label="Save"[\s\S]*? \S+=["']?(?:.(?!["']?\s+(?:\S+)=|[>"']))+.["'][\s\S]*?>[\s\S]*?<\/umb-button>/gmi;
                    if (resp.data.match(pattern)) {
                        // Remove the save button in it's entirety
                        resp.data = resp.data.replace(pattern, '');

                        //userService.getCurrentUser().then(function (result) {
                        //  return result.userGroups;
                        //}).then(function (userGroups) {
                        //  console.log(userGroups);
                        //});
                    }
                }
                return resp || $q.when(resp);
            }
        };
    }

    // add the interceptor, if it doesn't exist already.
    function addInterceptors($httpProvider) {
        if ($httpProvider.interceptors.indexOf('memberSaveButtonInterceptor') === -1) {
            $httpProvider.interceptors.push('memberSaveButtonInterceptor');
        }
    }

    angular.module('umbraco').factory('memberSaveButtonInterceptor', ['$q', 'userService', memberSaveButtonInterceptor]);
    angular.module('umbraco').config(['$httpProvider', addInterceptors]);

})();

Thanks Dave, I've made some further progress. I think I now understand why I was getting the circular dependency errors, see the link in my comments below. This is where I am at now:

angular.module('umbraco.services').config([
    '$httpProvider',
    function($httpProvider) {

        $httpProvider.interceptors.push([
            '$q', '$injector', function($q, $injector) {
                return {
                    response: resp => {
                        if (resp.config.url.toLowerCase().indexOf('views/member/edit.html') !== -1) {
                            // Use the injector to get the userService and avoid circular dependencies
                            // See https://www.codelord.net/2016/11/10/circular-dependencies-in-angular-and-the-injector-service/
                            var userService = $injector.get("userService");
                            userService.getCurrentUser().then(function(result) {
                                return result.userGroups;
                            }).then(function(userGroups) {
                                if (userGroups.indexOf("membershipAdministrator") > -1) {
                                    const pattern = /<umb-button[\s\S]*? type="submit"[\s\S]*? label="Save"[\s\S]*? \S+=["']?(?:.(?!["']?\s+(?:\S+)=|[>"']))+.["'][\s\S]*?>[\s\S]*?<\/umb-button>/gmi;
                                    if (resp.data.match(pattern)) {
                                        // Remove the save button in it's entirety
                                        resp.data = resp.data.replace(pattern, '');
                                    }
                                }
                            });
                        }
                        return resp || $q.when(resp);
                    }
                };
            }
        ]);

    }
]);

I am now fighting a new issue but too tired to make any further meaningful progress tonight. The new errors I think might relate to the callbacks: