If your Raspberry Pi OS or 'NOOBS' SD card is showing the wrong capacity when you plug it into your Windows PC - don't worry - this is very normal!
The Raspberry Pi runs a Linux Operating System (Raspberry Pi OS for example). When a card is formatted with the Raspberry Pi OS or another Raspberry Pi operating system, two partitions are created - a very small VFAT Kernel partition and a larger root filesystem.
Windows cannot read the larger filesystem so, to Windows at least, it doesn't exist! That's why your SD card will show a weird small size when read by a Windows machine.
If you no longer want to use the SD card for your Raspberry Pi and want that capacity back, just format it with the SD Formatter tool to enable you to use it again.