To Unload an Unused Linetype
Product Documentation
Intermediate
- Click

drop-down list. 
- In the Linetype drop-down list, click Other.
- In the Linetype Manager dialog box, choose the unused linetype, and click Delete.
Note
- Several linetypes cannot be unloaded: BYLAYER, BYBLOCK, CONTINUOUS, and any linetypes currently in use.
- Use the PURGE command to remove all unused linetypes from a drawing.