separating A/C Lines (see pic)

I've removed the clips which keep this A/C line together. However, they're not easy to pull apart.

Am I being limp wristed and need to just yank harder =or= is there something that I'm not doing right.

There is a tool that goes inside that fiting to push the spring that holds the fitting together. Then you can pull them apart.Will probly be pretty tight,so you will have to pull pretty hard.
 
A/C Tool

I was able to remove the outside clips by hand. So I presume you're talking about a tool that fits the items in the picture I included.

Can this tool be purchased from a good Auto Part Store (NAPA/O'Reilly) ???

Or will I need to go online ?

Thanks again