Removing a license isn’t an often requested feature. Currently you can write to email@example.com with your request and they’ll do it for you. Best to do this from the email you registered from for easy confirmation.
Now, about the issues you’ve experienced, it’s likely due to the recent problems with the service where forge hosts the Foundry instances using severe overprovisioning. Meaning they promise more resources to their clients than is actually available. We’re in the process of moving away from them and so far have taken the more expensive package to solve those issues.
Work is definitely being put towards making the service more stable during rush hours.
I hope this helped clear some things up and we’re of course sorry for the problems you’ve experienced. Soon they’ll be a thing of the past, but we understand your reasons for choosing self hosting.