Hi,
If there is no option to turn the WiFi On or Off in the Settings area, you may have to reset the tablet.
''Be aware that by resetting the tablet, (also known as a Hard reset) all your data and downloaded apps will be erased. It will be like when you first bought it.''
''Therefore it is '''important''' that you '''backup''' the tablet '''first''' before you perform the reset, so that you can restore it later if you wish to. Also ensure that the battery is fully charged before you perform the reset.''
Here is a link to the [https://static.bhphotovideo.com/lit_files/277156.pdf|user guide], in case you cannot find your copy. In it you will find information on how to reset the tablet and also how to backup the tablet.