Revo uninstaller has a Autoruns Manager in the Tools menu... See if it can disable the application before uninstalling it. Then click on Uninstaller > Select the application > click Uninstall > Confirm with YES > Select Advanced and click Next > wait for the program to finish uninstalling and confirm again with YES > and click Next > wait for ths "Leftover Information" scanner to finish > click Next > scroll down to the highlighted key names and expand them and only check highlighted subkeys and values, and click Delete > Confirm you want to delete the registry data > click Next > the next box is the leftover program files and folders, select them and press Delete and Confirm > Next > and FINISH. And immediately restart the computer specially if some files and folders can't be deleted and Revo Uninstaller wants to delete them during the Restart.
To clear misconceptions, you can't damage the registry by deleting keys from third party applications specially unwanted applications, their registry keys are not Windows keys and their files and folders are not system files... so you can't damage the Windows Registry or System data.
If still the application is not completely uninstalled, scan the system for virus and malware and individually scan the application folder in; C: > Program files > AVG PC Tuneup 2013 folder.
If it's still not uninstalled, post here the link to the website where you downloaded it from.