If the original installation of those applications required your administrator password, then they likely installed other application components outside of your application folder and simply moving an application to the Trash did not completely remove the entire application. If these were older 32-bit applications, and even if the vendor has an uninstall tool, it too might be 32-bit and unsupported on Monterey.
I would resist installing any so-called application cleaner apps as they may also carve valid files from your System.
When I want to thoroughly remove an application that has no uninstaller, I resort to using the Terminal application and some macOS tools to identify the files and locations that an application installed. If you are not familiar with the Terminal and nervous about using the UNIX command line, then I don't recommend you doing the following where the '#' is a shell comment:
# list of vendor packages installed
# example: com.adobe.DNGConverter
pkgutil --pkgs | more
# list of files and locations installed by the specified package
pkgutil --files com.adobe.DNGConverter > ~/Desktop/DNGFiles.txt
Then, one can go through that text file on the Desktop and remove the individual files not in the Applications folder before removing the Adobe DNGConverter application itself.
If you upgraded from an older operating system that allowed applications to install kernel extensions into /System/Library/Extensions ( a practice Apple no longer allows) and then upgraded to Monterey, those extensions can not be removed as Apple has the operating system now on a read-only, code-signed volume without any user privileges to remove items from it.
You may be able to remove some legacy application icons by rebuilding the operating system database (Launch Services) that tracks these. To achieve that, you need to boot Monterey into Safe Boot mode by pressing the shift key immediately from a restart or shutdown boot sequence. You will see red lettering in the upper right of the screen at the Safe Boot password prompt. After you sign in, just perform a normal reboot.