how to remove plugin

i have updated my one project for 4.14 to 4.16 version. Project need unrealjs plugin and hggifimporter plugin but they aren’t combatible in 4.16 anymore. When i try to package it failed immediately and said that ‘HGGifImporter’ plugin. Install it and try again, or remove it from the project’s required plugin list. How and where i find that plugin list?