Garmin built in POIs corrections?

You can report errors in the map data (which includes the built in POIs) directly to Navteq who provides the data to Garmin.

Navteq has an online tool for this express purpose.

http://mapreporter.navteq.com/dur-web-external/

is it possible to correct those poi's on your own...like delete or change the poi's address

Nope. Unfortunately not.

How often do these update? With each software update? or less than that?

Well, in theory the map data is updated annually, however, as with the road data, it can take a number of years for the POIs to be updated.

There is a location near me that was demolished over 7 years ago for expansion by the local university, and it still shows up on the maps.

Thanks MM, I've done my updates on the site.

By the way, it seems that "NAVTEQ releases navigation data up to four times a year to a wide range of navigation system manufacturers and vendors.", so it is unfortunately that Garmin only does it once a year.

I would prefer for them to update only once every two years and have accurate information not older than 12 months. Some of their road and POI information is many years out-of-date and they shouldn't be charging money to sell it as new updates.