how to delete installer for high sierra from catalina 10.15.3

so as you can see i have Catalina version 10.15.3 on a macbook pro

so the computer keeps saying i need more space ... but

there is nothing else delete ...

i found this file that i guess copied over from the timemachine backup

to the new computer ... and i deleted it

i tried to empty the trash doesnt work

i put it back and which it goes to applications but i am not able to delete it there either.

i have search all the forms in apple

youtube and i am at my wits end!

i have tired the safe boot and delete.

anybody can help me ?

i really need the space and the help from the community

i have enclosed a few screen shots....