The Kaspersky helpdesk gives the following guide to uninstall Kaspersky Mobile:
In order to uninstall Kaspersky Mobile Security (Android) from your smartphone, do the following:
In the main application window, select Additional--> Uninstall the App.
In the Uninstall Kaspersky Mobile Security window, tap Next. Enter a secret code on request and tap Enter.
In the Uninstall Kaspersky Mobile Security window, tap Next. Tap OK in the Do you want to uninstall this app? message.
Kaspersky Mobile Security is removed from your smartphone.
If I understand your question correctly, your stuck at the secret code part not knowing your secret code. I guess just uninstalling the app via the default android way will not work if Kaspersky has is own uninstall method. As far as I know, your options are as follows:
Try recovering your secret code via this page from the Kaspersky website (http://support.kaspersky.com/6102). After that, use the guide given above to try again uninstalling the app.
Giving your tablet a hard reboot. This, however, will get rid of everything so this is not the best option ever......
I hope it helps.