Then I suggest you re-install CrashPlan, and then the uninstaller should be there, and you can use it.
Otherwise, if you are comfortable working in the Terminal with Unix commands, you can play with things like
/bin/ls -dleO@ /Applications/CrashPlan.app
drwxrwxr-x@ 3 testing admin schg 102 May 29 11:32 /Applications/CrashPlan.app
com.apple.metadata:com_apple_backup_excludeItem 17
and see if it has any flags, such as 'schg' which is where the locked is coming from.
Then if you want to unlock it from the Terminal you could use
sudo /usr/bin/chflags -R noschg /Applications/CrashPlan.app
Password: <enter your account's password; it will not echo, but the Mac is seeing it; then press the return key>
After that it should be unlocked, and you can trash it easily.