If, when configuring the anti-theft (any version), you created a list of friends, you can disable the anti-theft by sending a corresponding SMS command from a trusted number. For more information about SMS commands, please follow this link.
If you use Dr.Web for Android 6.0 and didn't create a list of friends, you need to send a request to Doctor Web's Technical Support Service. In your request, you will need to provide the following information:
Your Dr.Web serial number
a photo of the box, warranty card, or other document that concerns the blocked device and contains a readable IMEI.