How to delete a line in a file

Say I had a file with this in it

Cat and dog ran
dog and cat run
dog killed cat
cat hugged dog

How do I delete the "dog killed cat" line with no empty lines between both the sentences.
Its so negative its hurting :mellow:/>/>

You'll have to read the entire file, put it in a table, remove the elements you dont need, then re-write it.