Your computer's clipboard is a convenient place to readily store data that you wish to copy and paste. It is especially helpful if you need to paste the same date in several places. There may also be times, though, that you wish to clear the clipboard.
Clearing Your Clipboard in Photoshop
Restart Photoshop. Every time you start Photoshop, the clipboard is cleared. This means that a very simple way to clear your clipboard is simply to restart the program.
Use the Purge command. Click the Edit tab, then Purge, and next click Clipboard. Your clipboard will now be empty.
Replace the clipboard with a small amount of data. If you placed a lot of data on your clipboard, you may find that your computer's processing time slows down. You can speed it up by finding a very small element, and then copying it. The clipboard simply holds whatever data was last copied to it, so if the last thing you copied was tiny, then your clipboard will only have a very small amount of data on it.
If you are using Photoshop Elements, the Purge command is called "Clear" instead.