Each social media site has a management section for 3rd party access given by the account owner. To revoke the permission to any application, the connection is managed from the social media site. 

Each social media profile will be different as far as where the management section is for 3rd party access:

LinkedIn - HERE

Twitter - HERE

Instagram and Facebook - HERE

YouTube - HERE

Google - HERE

Note: Updates may not be in real time, please allow time for system changes.