How to merge divided surfaces?

Hello - very simple questions - 2 surfaces were created in this bar. sketch up of course does not allow to cancel the line which divides the two areas without its bugs. what to do? which tool to use to merge or not make sketch up think i wish to cancel the surface by canceling the line???

Most likely the surface isn’t flat, and therefore the line is there to indicate where the surface is bent. Removing the line results in a surface that can’t fill in as its edges are not coplanar. The solution is to model the bar so that you have a truly flat surface, and when that is done, you simply delete the line.

If you want to keep the bent geometry, but don’t want to see the line, you can simply smooth it away with the eraser tool (shift click).