I installed yesterday Affinity Photo and while I was exploring the software I was using the column guides. When I wanted to hide them I couldn't find any option so I went to the Affinity Photo Help to look for it. On the Ruler and column guides page there is written:
However, as you can see in the next image there is no such option. The only way to remove the column guides is to remove it manualy on the guides manager.
I'm using Affinity Photo ver. 1.9.0.932 on Windows 10 Home 64-bit.