In your domain manager, there's a link that says
set
domain locking
for this name using flyLOCK
But, to do a bulk lock/unlock, you have to put in a support ticket.
I'm clearing out my regfly names, and just went through this with them yesterday. Easiest way is to put in a ticket, especially when you have to modify a lot of names.
They offer bulk modification for certain other aspects of domain managment, but bulk locking is one of the features that they lack. Unless, of course, you put in a ticket.