Jonathan,
Take a look at this post Solution for adding or removing records from table hosted in AGOL? It explains how to edit features on AGOL feature services from ArcGIS Desktop and Pro. You can also directly Edit features in ArcGIS Online. All of the above requires that editing is enabled on the AGOL feature service settings for the user or group making the edit. You can also edit your data in a local database and republish the service to AGOL. We do this nightly via a script for our enterprise feature classes.
On a side note, are all your manhole points somewhat shifted in the same direction and distance? You may have a data shift resulting from a translation error between coordinate systems of your data and the imagery. If the data displacement is random it is most likely an accuracy issue.
