How to cut off extra lines in Affinity Designer, leaving only a closed square?

Question

PHP

spoiler

Answer 1

Can you describe your question in a little more detail?
(Or attach a picture of how you imagine it)

Answer 2

Affinity Designer has several ways to cut a vector object, both reversible and non-reversible. Which one to use depends on the task.
I made a video on this topic. You can see here.
https://youtu.be/nWamprxbjhs