Could someone help me solve the problem protecting word template with password.
I create word template that is connected with excel file, and try to protect word template from editing or deleting structure of document (only mailing - finish & merge to be enable).
Thanks in advance for help

The 'template' you're describing is a mailmerge main document. You cannot apply editing restrictions to such a document.

You could apply a password for modifying the file, setting the 'read-only recommended' property, or apply the Windows read-only attribute to the file, but all of those only prevent an unauthorised user saving any changes they make; it does not prevent the user making changes, then running a mailmerge with those changes in place.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

If you have saved your main merge document as an actual Word template, your user's can use it by creating a new document based on the template. You can make the template read-only. That will not prevent changes to documents based on the template.

More nuanced methods of protection do not work with merge documents.