Tires won’t come off rims
It may be that your rims are "tubeless ready" which means they have a lip around the side that the tyre slots into which makes an airtight seal but does make them harder to get off. You should be all right if you let the tyre down completely and then push the edges of it towards the centre with your thumbs to pull it out of the slot. Once a bit of it's free the rest will usually pull out easily.