Open Discord and go to the server
Click the server name at the top
Select Server Boost
Open Your Boosts or Manage Boosts
Click Cancel Boost or Stop Boosting
Confirm the cancellation
If you boosted through Nitro, cancel or change your Nitro plan in User Settings
If you boosted through mobile, manage the boost from the Discord app subscription settings
Wait for the boost to expire at the end of the current billing period