Hi to everyone ...
to remove media from node and from Media i use

mediaService.Delete(media , 0);
content.SetValue("image", "");
contentService.SaveAndPublish(content, userId: 0);

it seems like ok, but you will get error here :

string img = Model.HasValue("image") ? Model.MediaById(Model.GetProperty("image")).Value).umbracoFile : "";

The result of HasValue is true!! .. the error you will get is "Object reference not set to an instance of an object." .

but when adding this line you will not get any errors :

umbraco.library.RefreshContent();

In other hand if i use MoveToRecycleBin() instead of Delete(), here we no need to use "umbraco.library.RefreshContent();" .

mediaService.MoveToRecycleBin(media , 0);
content.SetValue("image", "");
contentService.SaveAndPublish(content, userId: 0);

so the Delete(media) should use refrechContent(), but MoveToRecycleBin(media) no need to use refrechContent().

for a good performance:

• which one is better to delete image.
• and should i use refreshContent() when updating content.

Note : umbraco version is 6.2.4

thanx ..