How to modify this sidebar code?

I have a blog https://www.infosanta.com/. Bt the problem is the theme i’m using doesn’t allow me to remove the line “Click here to get the best wordpress themes by Bestpremiumwp.com.” on the right sidebar. whenever i try to remove this the theme gets deactivated.the same thing happens even if i modify the code over there.please help me out.i don’t want that on my blog.thanks in advance