If you don't need to notify a contact of your visitors' arrival or are looking for a modern version of a sign-in sheet only, we can do that!
Start on the buttons page of your online dashboard. Select 'Existing Buttons' on the right then click to edit your sign-in button. Scroll down to the 'Select Employee Contacts' section. The last option on the right will 'disable contact selection' and set your button to simple sign-in only behavior. Enable that feature and save at the very bottom: