It's not recommended to flush Viva paper towels or any other paper towels because of the potential to clog the toilet and sewer pipes.
However flushing one paper towel whether Viva Paper Towels or other brands should not cause any problems because I've done it before.
However I don't flush a lot of paper towels unless I had to use it to wipe up poop or something nasty that I didn't want to put into the trash can.
Then I would flush the paper towel and flush the toilet a few times to force it down and out of the toilet and sewer pipes.
Flushing more than one paper towel at a time could cause a clog in the toilet.
It's best to throw the Viva paper towels or any other paper towels into the trash instead of the toilet to avoid clogging it but if you must flush a paper towel only do one at a time.