Depends on what the application is, basically you need to look at the application and what uninstall command lines it supports. Basically it should be possible unless it needs to be de-registered from a console first eg some corporate antivirus software is like this.
usually a password in a file installer is required only to unpack the file contents. If this is the case you can use the unpacked files or use the uninstaller saved in the msi database or in the installation folder.