When you can not uninstall Kaspersky Internet Security by yourselve, you may try some third-party uninstaller to help you. Take IObit Uninstaller as an example:
Step1. Open IObit Uninstaller, if you don't have one, you may download from page:
https://www.iobit.com/en/advanceduninstaller.php and find the Kaspersky Internet Security at app list:
Step2. Click the right uninstall icon to begin the uninstall process:
Step3. Click "Uninstall" at the pop-up screen:
Step 4. Click "Yes" to continue the uninstall process:
Step 5. After that, click the Powerful Scan to detect the leftovers:
When no leftovers detected, you've completely uninstalled Kaspersky Internet Security. Congrats!