I lost my Lumia 535. Is there any way to block the phone to not allow anyone to open and use it?
You can see the list of devices associated with your Microsoft account at the following link:
Find your phone in the list and click on "Show details". Then click on "Find my device", and from that screen you can make your phone ring loudly, as well as lock or erase it.
For more information, see this MS help page: