The easiest way for preventing this machine from getting new work seems to be to set your preferences to values that exclude it (e.g. "use no more than 0k of disk space" or similar).
The credits are bound to your account, not to the machine, so you will keep them.
BM

planed to detach machine, howto?
)
Sounds good in general, but remember that the localized profiles are somewhat broken in the 4.19 client.
Actually I've never done this myself yet, so I don't know the best timing for it - I remember an older thread discussing this, but can't find it righ now.
BM
BM