Do you mean: Delete the shore line after chart interpolation in RM (others make no sense)?
If yes, RM create 4 shape-files. The shore line infos contain in 3 from 4 shapes, not in *_minor.shp file.
You can delete shore line elements in GIS application e. g. QGIS (freeware)
- Open qgis and load file
- Open attribute table (right click on file name)
- Push edit button
- Mark the shore line
- Push delete object button
- Push edit button again and save file
- Result - the line is deleted
- Repeat this with the other 2 shape files
- Now You can use the IMC
Best wishes
fjordfisher