II dev here. You raise a good point. Thanks!
There is now way to do it right now. And I agree that 30 days is very long for a non-revocable credential.
So far, the SDK team has addressed this by implementing idle timeouts. However, this is also a client side solution and can be controlled by the developer.
To give users more power, we would have to switch the way delegations are issued to make them revocable. We do have plans for that, but unfortunately have not yet had the time to address it. But it is part of the current set of requirements in the working group discussion about interoperability with regards to identity (R5).
TLDR: We are aware of the issue and are working on a solution. But resources are tight, so it might still take a while.