However, if you want to do it you may be able to edit a copy of a preset file and save it as a new preset. The presets are text files. I did it once several years ago and got it to work. There are no guarantees of success!
To find the technique, do some googling.
You may find something like this or versions of it:
"In Windows explorer navigate to
Adobe Premiere Elements 14
Copy/paste and rename DSLR 1080p25.sqpreset (give it an unique name)
Open Notepad (as adminstrator) and navigate to this new preset
Change 1920 and 1080 to the desired dimension (e.g. 2.35:1 is 1920x816)
If you are using non matching footage check "Force selected Project Settings on this project' in the New Project settings otherwise it will change to the dimensions of the first clip dropped in the timeline."