Extracting outer boundary of polygon (current polygon merged to one row but layer has holes creating small polygon needing removal) using ArcGIS Pro

A simply way I remove holes from a polygon is to:

1] Go into edit mode and select the polygon

2] Click on modify button

3] Click on Edit vertices so vertices show up as green dots

4] In the modify panel your outer ring should be part 1, all holes are parts 2+.

5] Simply selecting a vertex will confirm this for you. Look for the flash on the screen.

6] Select all vertices in all others parts and click on delete (red cross)

If you have millions of polygons with millions of holes (which you don't actually say) then a python solution would be a better solution. Just search this forum.