Troubleshooting / Help with Lospec Pixel Editor


I am new to pixel art and the Lospec Pixel Editor is the first program i've ever used. I'm trying to figure out how to use the "trim" function on the program and have not been successful... I can't find any tutorials or help threads that are more recent than 2018 on the pixel editor program since the layout and functions have very clearly changed over the last several years. Can anyone help me with this?

:ah: Thank you!