This happens when there is a previous installation of VPN on your machine.
First check if it is still installed:
- From the Finder go to the Application folder.
- Look for the "Cisco" folder and open the folder
- Then double click on "Uninstall Anyconnect" start uninstall process
- Follow instructions to uninstall VPN program
- Reboot
If nothing is there here is the procedure for manually uninstalling the AnyConnect client:
Run the following shell script from the Terminal:
$ sudo /opt/cisco/vpn/bin/vpn_uninstall.sh
You will be prompted for your password. Once you enter it, just follow the steps and reboot.
If you are still having problems try this from the terminal.app and reboot:
sudo pkgutil --forget com.cisco.pkg.anyconnect.vpn
More detailed instructions here:
http://kb.mit.edu/confluence/display/mitcontrib/Cisco+Anyconnect+Manual+uninstall+Mac+OS