I have this intersection of a polygon, see image below
I would like to redraw the lines so they don't cross each other.
So, in the end, I would like to have a polygon without self-intersecting parts. How can I accomplish this?
vertex tool is what you are looking for. Select the polygon layer you like to change and go into edit mode. Then choose the vertex tool and click on the vertex you like to edit. You can either move it or delete it. By clicking on the
+ between two vertices (while hovering with your mouse) you are able to create a new vertex.
By the way: It works the same way for line layers.