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 you can use the following to do a "Hard Reset".
NOTE: Doing this will clear 'all' the data on your tablet, so it is suggested you not choose this option unless you have to, or aren't worried about losing anything on the device.
Be sure you back up any data you want to keep, to a computer or cloud account, before doing the reset.
To "Hard Reset" the tablet...
1. Make sure that the tablet is actually powered off.
2. Remove your SD card, if there is one in the device.
3. Press the "Power" and the "Volume Up" buttons, together, until you see the start-up logo on the screen.
4. Once you can see the logo, release the buttons and allow the device to enter the "System Recovery Mode".
5. Next use "Volume Down" button to get to the "wipe data/factory reset" option.
6. When in recovery mode the "Volume Up" and "Volume Down" buttons are how to can navigate and highlight what option you need.
7. Once you have selected the "wipe data/factory reset", press the "Power" button to select that option.
8. On the following screen, repeatedly press the "Volume Down" button until the "Yes - delete all user data" option is what is selected.
9. Then press the "Power" button to hard reset the tablet.
10. If you took your SD card out in step 2, when the device is up and running again, reinsert the SD card.