Rommel, I don't represent Upwork but I see no reason why you can't. Just remember though, if it's an hourly job, not fixed price, and you do not allow manual hours, the computer the freelancer uses has to be connected to the internet and must have the Upwork app installed on it.
There are different opinions about this. Some people do think that this should be totally forbidden and they'll report jobs that they feel ask freelancers to do onsite work.
Personally I have no problem at all with the concept.
As long as you don't make waves or cause problems with this, you should be fine.
(I'm just an Upwork user. I don't represent Upwork either.)