How to remove gaps in one polygon

[Anonymous User]

I am trying to make metersheds from a parcel layer. I want it to be one continuous polygon with no gaps throughout it. Is there a way to do this without having to re-draw every basin? I have tried using Interpolate and also Aggregate Polygon. 

[JoeBorgione]

If you have an advanced license you can try the minimum bounding geometry with the convex hull option.  I just did it Pro. First merge all your metersheds into one polygon and then apply the tool.  You'll still need to do some trimming:

My original:

Minimum Convex Hull:

Trim to your liking: