The phrase 'to see the back of" means that you'll be glad when somebody leaves because you do not get along or do not like that persona.
Example in use: "My sister-in-law became an absolute pain, I was really pleased to see the back of her."
Interesting fact about To See The Back Of
This phrase is popular at the end of the year when friends encourage each other to share their thoughts on: "What will you be glad 'to see the back of'?"
