Apparently, Prism Launcher chose to adhere to the idiotic principle of the hidden "trashbin", .Trash-$(uid), invented by Ubuntu. Even though it's based on QT. This can't be disabled. It accumulated 139 GB of literal Trash, fully replaceable, over time. Just ... why? There's even an open issue about this, for over a year, referenced multiple times. I guess I have another point on my agenda.
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
Depending on your file manager, you may be able to hold Shift while triggering the delete to get a hard delete.
Shift+Del is pretty much standardized as the keyboard shortcut. And here on KDE, I can hold Shift while clicking the "Move to Trash" menu entry, too (well, it actually replaces the menu entry with one for permanent deletion, but that's effectively the same).