I personally rinse it under the tap and wash my hands so the soap goes into the plastic bit and I let the tap run very hot to get rid of the residue if I can't get it off with the water I then use some toilet paper to wipe it off and go back to rinsing it
I sprayed some dettol in there and wipe with toilet tissue.
I’ve just ordered some potty liners from Amazon, you just place it into the potty and when your little one is done, you take out like a little bin bag and put it into the bin.
I use toilet tissue and then flush it and once 'clean' I then use an antibac wipe which goes in the bin. You could try bin liners but then you have to decide if you are going to throw the poop in the bin or turn the bag inside out into the toilet