Potentially daft question and in the absence of a housekeeping section this seemed the best category.
Got one of the vinyl bedsheets from the mighty LH enjoy the sensation and usually a decent wipe keeps it clean . How on earth can we get the creases out of it ? Even from the initial postage and storage always has creases in it.
You could try warming it gently with a hair dryer while it’s laid out flat.
Maybe a steamer might work
We put ours in the washing machine and then hang up to dry somewhere warm. I don’t think you ever get the creases out fully.
Warming with a fan heater would work. However, just leave it you’ll possibly cause more damage lets fsce it, it will crease as soon as you rest on it?
Thanks all… Heat seems to be the key but making sure not too hot I guess (In the temperature stakes not the in action stakes 
I agree with others use a hairdryer on it and stretch it
I think there is only so much you can do. It’s only going to crease again when it’s packed away