AutoPLANT does not have a mechanism to delete user annotation from the AutoCAD. User annotations are stored in 2 text files in the project. To delete the user annotations they must be manually deleted using the following steps.
[Test]
Format=Test Size is <<MAIN_SIZE>>
isUserFormat=1
annoText=Default User Formatted String Annotation
textFunction=Ann_FormattedStr_Method
textFormat=Test
annDescription=Test
Once the user annotations are deleted from the 2 files they will not show in the user annotations section in AutoPLANT.