Hi and welcome. Being a part of the Brave community can be frustrating. Been there several times myself. Going to post the instructions and forms for unlinking a device. Support staff notify you via email when they open a slot.
ISSUE: Device Limit Reached
This link is for Instructions and a link to the Request form to Unlink a Device :
How to Submit a Wallet Unlinking Request
Detailed Instructions with Screenshots below:
How to Remove Verified Devices (screenshots)
Thanks to @Herrvader for the screenshots. 
Context :
How many Brave Rewards wallets can be linked to my crypto custodian account?
Brave is removing linking limits. Hopefully soon.
Brave GitHub Issue Report :
Implement solution for linking limits
Update (Linking Limits):
04/20/2022
Comment by Miyayes (Issue Author/Brave-Browser Collaborator)
