i tried to remove this idle perk point using export/import mod. interestingly, it wont do, and u cant even edit ur smithing skill lvl, i tried to edit it to 270ish, but once back in game, its restored to 301 lvl. yet any other changes i made are perfectly fine.
I can confirm this, 1 extra perk to spend with all already selected. Minor, but present. Character import/export mod may cause this bug, but worth checking