The toilet seat has rusted away the screw holes that connects itself to the iron hinges, making the seat removable while the lid and the hinges stays connected to the toilet bowl. I want to remove the hinges and the toilet seat (+ lid) but the hinges have become so rusty that when attempting to remove the cap beneath, the screw rotates with the cap.
I've tried holding the screw head with slip joint pliers but it's so flat and that it's fitted so tightly making it impossible to fix it in place. I've also tried adding lubricant but it's not working.
Try to get a hacksaw like this one.
You can slide it in under the hinge and cut through the rusted bolts. You will need to pull on the seat to keep the bolt from turning as you cut.
If you can not find one with a handle then just use a blade without a handle and wrap a towel several times around the end you will be holding, wrap the towel tight and use tape over it.
You could slide a thin piece of card or thicker paper between the blade and the porcelain to protect it from the blade scratching it.