This is for PC, let me know if you're on a Mac
1. You need to delete everything in this folder C:\Users\*username*\AppData\LocalLow\Glitch Pitch\Idol Manager\data\cache\portraits
2. This is how your Mods folder should look like:
Also, make sure to delete everything in cache\portraits again before playing without the mod
I will likely make it more convenient in the future, but for now you have to:
1. Delete everything in ~/Library/Application Support/Glitch Pitch/Idol Manager/data/cache/portraits
2. Find the game .app -> right click -> Show Package Content
Copy "Default" and "idolskins1.0" into Contents/Resources/Data/StreamingAssets/Mods/
