How do I remove Bussman SL15 tamper proof fuses from my Edison base
socket without damaging the socket?

I think you will find that they simply screw out. Might be quite tight.

Best

The whole pupose of "tamper-proof" includes removal.The base includes
a spur which digs into the edison base.Any attempt to remove will
damage the base,creating a dangerous hotspot in the circuit.
 The 'S' type fuses prevent a potentially dangerous situation where a
homeowner might try to overcome a faulty circuit which is blowing
fuses on a regular basis,by installing  a higher ampacity protective
device into the base.This has been the cause of many fires,as the
wiring itself can become the weakest link in the circuit.ie,it could
burn up before the fuse link does.
http://cipco.apogee.net/foe/fsgotsf.asp

Aye ?electrocutioner? (great name), but it?s only the adapter which
cannot be removed -- it?s function being, as you say, to prevent fuses
greater than a certain rating being fitted. The fuse can still be
removed for replacement by unscrewing. Agreed?

Best