You can set up a password to prevent people from moving between Self-Registration and Admin Mode.

See this article for instructions on moving between Admin Mode and Self Registration Mode

Setting up the password

In Admin Mode, navigate to Options > System Setup > Self Registration 

In the Layout section there is a field called Password

Enter your password into the blank field. It is automatically saved. 

Using the password

To move to Admin Mode from Self Registration Mode enter the password into the name field. 

Leave the cursor in the name field and click/tap the VisitorRego.com text in the top left (or bottom right of older software versions)