Changing footer.php in Atahualpa to remove rhs sections?

Hi,

I’m using Atahualpa theme. I wanted to remove some sections on the rhs, so I went into the Admin -> Appearance -> Editor and edited the file Footer.php to comment out the lines of code that were showing the ‘Recent Posts’ and ‘Meta’.

Now I’m just wondering what will happen if / when I upgrade my theme when a new one comes out… I presume my changes will disappear? How do I prevent this?

Many thanks,
WP.