Once you've paid for the protection package (as in, Rover shows a negative balance for the amount of the plan in your account), I don't believe you can return it. However, it would be worth contacting Rover Support to doublecheck before your first stay begins to be sure.
I agree with Daniela that you should very quickly raise your rates to something just below average for your area. Rover shows you the average cost per night for your zip code on the Profile tab. I would also recommend keeping the protection package, especially for your first year of business. It gives you a badge displayed on your profile (and in the search rankings), and it gives you a boost in the rankings, which will help you be noticed by potential clients. I like to think of it this way: the protection package is $50. At my rate, if I book 2 extra nights per year because I'm listed higher in the search rankings, or my profile looks more appealing to customers, then even with Rovers fees taken out, the protection package has paid for itself, and I have the benefits it provides me all year long, should I need them. Even at your current low rate, you still only need 4 extra nights that you wouldn't have otherwise booked to come out even, and over the course of the year, that's not a lot.