Yes, you can cancel your subscription at any point in time.
To cancel your subscription, click on the user icon at the top right-hand corner within Ubersuggest PRO:

Next, go into Account Settings and click Delete My Account:

Your subscription will end as soon as your billing period ends.
If you are paying on a monthly basis, it will end in less than 30 days.
If you are paying annually, it will end after the 12-month period selected.