multi:RemoveHandle(handle)
When the easy handle has been removed from a multi stack, it is again perfectly legal to invoke easy:Perform() on this easy handle.
Removing an easy handle while being used is perfectly legal and will effectively halt the transfer in progress involving that easy handle. All other easy handles and transfers will remain unaffected.
It is fine to remove a handle at any time during a transfer, just not from within any libcurl callback function.