It wouldn’t have added it for no reason. If you tap on “activity” you can see the transactions which make up the additions and subtractions to the category for this month. (And I see that it says $0 but that just means it’s netted to $0.) 

If Budgeted and Activity are zero, then it carried over from a previous month, just like any other category.

Pink Yeti said:
How do I remove this amount and set it to zero?

Same as with any category:

• Hit the Reset Available Amount Quick Budget button
• Budget -1.86 (positive values increase Available, negatives decrease it)
• Click on the Available to access the Move Money tool