Trim A String - Removing the last 3 Chars

If I had strings such as below in my fields - how can i remove the last 3 chars

String 1 (1)
Test (2)
please remove the last 3 chars (3)
omg this is hard (7)

i been playing around left, right , ltrim and rtrim but i cant figure it out. so based on the above my fields should return

String 1
Test
please remove the last 3 chars
omg this is hard