I'm just wondering if anyone has experience ending their HAP, is it as much of a long drawn out process as applying for it in the first place?
Depends.. I presume you are the landlord. If so, it follows similar pattern to ending any tenancy I.e. you need to state the reason to end the tenancy e.g. Sale /self use etc and follow the correct rules around serving a notice of termination /time limits etc.
I read it that the OP is the HAP recipient (as in tenant). Also , kandlords do not apply for HAP.