Hue discovery having issues to find changed groups

hi, i needed to reavulate stuff in my hue-bridge and changed a lot of stuff. I figured that the changes do not sync at all to openhab. The only possible way to “rescan” and “rediscover” is to manualy delete all hue items and do a full discovery again.
a) is there an easy way to remove all things from one binding?
b) is there a way to “sync” hue things with changes on the bridge without the need to do a delete-first action?

Newly added Groups seem not to show at all when having more than 4 groups - it seems - can s.o. verify this?

Thanks in advance