Cannot Delete Locked Application

Hi friends, I am struggling quite a bit here...

My university uses ForiClient VPN to allow students to tunnel to servers which are sometimes necessary for schoolwork. I hate FortiClient as it is invasive software which always wants to be running and lives in the menu bar and starts up every time I boot my Mac. Typically, I will install it when I need to use it, then uninstall it immediately after. As the semester comes to close, I was cleaning up the old MacBook and I tried to uninstall FortiClient as I normally do. This time, however, the uninstaller simply froze when I tried to run it. I tried to uninstall it multiple times without success. I rebooted, and tried again with no success. I proceeded to use a third-party app called Sensei which has an uninstaller feature with no success.

I tried to delete the file but it told me it is locked.

I opened up Finder > right click on FortiClient.app > Get Info and while I have read/write permissions on the file, I cannot remove it because it is locked and greyed out.

Next, I moved into Terminal. I followed the steps in this nearly seventeen year old discussion post [how do i delete a useless folder when "lo… - Apple Community] without success.

It looks like it did something but the file is still locked.

I also tried deleting it how I would delete any other directory in Terminal without success.

Again, it looks like it did something but the file is still there.

Next, I put the Mac in Target Disk Mode, connected to another Mac and tried a lot of the same steps in Terminal without success.

Next, I created a new Admin account and tried many of the previous steps without success.

Next, I created a new folder on the Desktop and called it FortiClient.app. I was warned about changing the extension to .app. I dragged the new fake application to the Applications folder and tried to override without success.

At this point, it appears that both the FortiClient app and the uninstaller app have been mostly deleted, they are now just locked folders. However, when I try to install a fresh copy of FortiClient on top of it, it tells me:

I really don't want to do a clean install because that is a lot of work and I am lazy, but I am quite upset that the FortiClient devs think it is necessary to lock these two files— I understand if they were company owned, but this is my personal device. I would much prefer logging in with credentials which are natively supported within macOS and without requiring garbage third-party software, and I will be submitting this feedback to my school. If anyone has any tips, please let me know, it is much appreciated!