A trial licence is fine for testing some stuff, but if you need to remove it, for example when it causes you issues in a stack when the master thinks it on perimeter, but the backup is not.
Remove Licence (Option 1)
debug epm clear trial-license
https://extreme-networks.my.site.com/ExtrArticleDetail?n=000001267
Remove Licence (Option 2)
debug licMgr disable DEF-EVAL-PRMR
debug licMgr uninstall feature DEF-EVAL-PRMR
https://extreme-networks.my.site.com/ExtrArticleDetail?an=000092952
Verify Current Licence
show license
show license slot X
Removing Stacking Licence Level
unconfigure stacking slot 4 license-level