Loosen & remove top cap & stem
Fork may then pull out but more likely need a whack or two with a rubber mallet/block of wood on the top of steerer to loosen the headset wedge thingy (Assuming here it’s an aheadset and ain’t made by Christaltips King). Once the steerer has pushed through a bit you can push it back up – the wedge should rise with it & be easily removable. Crown race can stay on the fork.
Be careful how you hold/brace the frame while whacking the steerer so you don’t scratch or dent it – best way, I think, is to invert frame & hit the steerer onto a lump of wood that’s on a bench (try to avoid poking yer eye out)
NB if you hit steerer hard enough I suppose the whole fork could shoot out & damage something but never happened to me – I guess you could “tie it on” with an inner tube or something if worried
Putting back – make sure you keep the headset bits in order (may well drop its (hopefully sealed unit!) bearings out when the fork comes out, so be careful & then use something (string, old inner tube, chicken entrails) tied through the head tube to hold it all together)
