Q:

Where can I see attached custom event receivers?

I'm completely new to the SharePoint world and I've inherited our SharePoint (or at least the development side of it).  Most of my trouble at the moment stems from finding things.  
This project has a few custom event receivers installed/registered/setup to lists I assume (whichever is the correct terminology).  
Within SharePoint or the SharePoint designer, where can I go to view these event receivers that are attached to a particular list?  How are they removed?  Given the solution and source code for the custom receiver, how are they installed/registered within SharePoint?

A:

You need to execute code to see these event receivers, but fear not, there are some great tools that do most of the heavy lifting for you. I am going to suggest you download the Patterns and Practices PowerShell Cmdlets from github. Install the v15 installer if you're using on-premise SharePoint, v16 for  Office 365. You do not need server access to run these commands.
Once that's installed, open a PowerShell shell and type in the command:
Get-SPOEventReceiver -List "My List Title"

...but before you do that, execute this to get a web context:
Connect-SPOnline -Url "https://siteUrl"

despite the name of the Cmdlet, it will work with on-premise SharePoint. You'll get prompted for credentials. You probably need to be a site owner or administrator to enumerate the event receivers.
While you're at it, this package gives you tons of great commands to do all sorts of things. Check out the documentation at https://github.com/OfficeDev/PnP-PowerShell/tree/master/Commands

