Register the annotation feature class as versioned and set permissions in ArcCatalog for users to have only select privileges on that annotation feature class. You can still select the annotation features using the "Select Element" tool, but nothing will occur if the user tries to delete the feature. The user can still open the text editor window by double clicking on the feature, and can change the text in the window, but when the user clicks OK they will receive a permissions error.i.e. Element update failed.Insuffiecient permissions[fc name][STATE_ID=<editing state id>]