before I would sign off their request for removal of the restriction.
Under EASA there is nothing for you to sign.
A CFI/HoT can, obviously, influence how and when a restricted FI gains
the experience required to remove their restriction.
Once an FI(R) has the required experience they apply directly to the CAA
to remove the restriction - no involvement from ATO, HoT or CFI required
for this Licensing action.
Just because an FI is no longer restricted it does not mean that the HoT
of an ATO cannot require them to still be supervised, if needed, whilst
instructing for them.