Rebooting a tablet is just turning it off (no power) and turning it back on. I am going to guess you meant to say 'reset' the table?
If you did in deed mean reboot, as explained above, then you can't do that from the internet. Actually you can't 'reset' it that way either.
Both of these need to be done in person. Now if the tablet was elsewhere, and still on, you might be able to do one or both of those, but you would have to have preinstalled apps on the device to get that to work, and it would have to have been an app that allows remote access. There are some of those, but you cannot do it after the fact, it has to have been done before. Can't install anything after the fact.
If you do have it with you, or have access to it, then...