@Snellman @mzak Welcome to the community. 
If you follow the instructions in the post linked below you can remove a device. I have also posted additional information relating to this issue. Hope it helps!
This Help Center article has more information on linking limits:
How many Brave Rewards wallets can be linked to my crypto custodian account?
Brave is removing linking limits. The Brave GitHub issue report is linked below. You can track the status of the project there. Anticipated release date is after May payout processing but there isn’t a firm release date set.
Implement solution for linking limits
Last Update: > Comment by Miyayes (Issue Author/Brave-Browser Collaborator)
Thanks to @IanMoone for image!