If it is a PC, go to My Computer, then Control Panel and there should be a "program" that is for installing and uninstalling programs. You can delete programs from there. But, the computer will still have to have certain programs on it to operate, drivers, etc.
You might get a separate hard drive that plugs into your computer at a USB port. You can store your photos on there until you need them. They are pretty reasonable (Amazon) and very useful for back up.
If you move the photos to another hard drive, or flash drive or whatever you can get for storage, then you can reformat the hard drive but you will have to have the WIndows disks to reload the operating system on your computer. If you Google how to do it, you will likely find detailed instructions on it.
There could be any number of things wrong with the computer, virus, failing hard drive etc. If that happens you may lose all your photos anyway so it may pay to get a storage drive or several flash drives to save those.