Are portals ever deleted?

I'm pretty new to Ingress and I noticed there's a huge amount of portals in my city. I don't mind that much, I just wonder: Are portals ever deleted for any reason?

Yes, portals can be deleted. Recently in Germany all 2nd world war concentration camps have been cleared of portals. This is a rather unusual case though. But portals can be deleted by reporting them.

If you feel a portal is against the rules (e.g. I have seen grass and standard road markings...), is removed from the real world or is in a dangerous location, you can report it to Niantic:

• In the scanner app by tapping on the image, then hit the "Edit" button at the bottom and then you'll find the option to "report invalid portal".
• On the Google support page (might go away soon now that Niantic has departed from Google): Click "Contact Us" in the top right corner, then "Report an issue with a Portal or a Mission" and then select a reason.

While the portal is removed from the game world, I believe your stats (unique hacks & captures) will not be decreased.

Here in town, we're doing a lot of construction. With that construction, a lot of different portals have been removed, since the construction has displaced the historic marker for the portal and it's become impossible for anyone to use even foot traffic to get to these location, unless you were a construction worker.

I honestly don't know what the protocol is for submitting a portal to be removed, but it's happened here in my city and I'm sure it's happened elsewhere. But for a fact of being deleted? I doubt it would be totally deleted from everywhere. But portals can, and have been, removed before.