Welcome to the board XDannyBoyX

Yes, you can.

You can use the magic wand tool and select one color by clicking on it (make sure that contigous is NOT selected in the top bar).

A second way is to select the color using Select / color range.
Just click in the select box to see what kind of options you have and adjust the fuzziness (=range).

After you have selected the color (either by using one of the 2 tools) you can press Delete to delete the content of your selection or fill it with a new color.

There are many ways to select/remove/replace colors, but I think these methods that I showed you are quite simple to use, even for beginners.