Hello I was wondering, all the workflow which actually are running in the FIM2010 can be managed by Administrator and how?.. I mean workflow operation like "Retract", "Assign to", and Etc? regards, Maqsood.

A lot of this functionality it built into the WF activities and cannot be controlled. You can cancel running WF instances by cancelling the parent request -this option is exposed within the Requests page, i.e. select and click Cancel. Note that cancelling action WFs won't rollback changes to the original state. WFs are not transactional.