It's always been the case that only those who don't/haven't owned a property before can use funds in a LISA to buy a first property. But they can be used by everyone under 40 for long term investing.
What you do now probably depends on how much you put in to the LISA and whether or not you will need it for a property. If you put a few hundred quid in there, you might have inadvertently made a good long term decision for retirement investing, might as well leave it there and add too if/when you are in a position to do so. If you put in a few thousand and you need those funds soon, you'll take a bit of a hit when if you withdraw the funds but it's only going to be a few hundred quid. Probably sounds painful now but not the end of the world!