You're doing fine, friend
Back in your OP (OP= Original Post or Original Poster) at #1, the "error" warnings were multiple because the packages Linux was updating for your Chrome, which comprised binary AMD64, binary All, a locale file (set to Canada where I take it you are from), and an English file. One warning for each package, lucky it wasn't updating 60 packages, lol.
Also, the numerals - you'll see there references to google-chrome.list:3, and google.list:1 - these are the lines in the respective files which are duplicate and generate the Warning.
Compare that with the last Post you have provided us, and you can see it is that line starting with "deb" for Debian.
So you want to get rid of one of either google.list or google-chrome.list.
To actually get rid of the files in /etc - which is owned by Root, you either have to assume Root (sudo su), or else use sudo, I would suggest sudo.
So either of these will work. First cd back into /etc/apt/sources.list.d and then
Code:
sudo rm google.list
#OR
sudo rm google-chrome.list
BUT (Wizard always has a but), without my knowing if either of those files is involved with dependencies related to other packages, I would be more inclined to either "save as" the file targetted for elimination, or else simply to comment out the offending duplicate line in one of them.
Given you are in 'Serena' Cinnamon, your default File Manager is Nemo. So I would suggest opening Nemo and from File System, tunnel to /etc/apt/sources.list.d and check the date-time stamp on each of the two files and report them back here. If your configuration is displaying icons for folders and files, click the icon near top right for list details.
If your List Details does not show dates and times, add the item from right-clicking the headers, as below
The more recent of the two files is more likely to be "the offender", and then we can take that & place a # in front of the offending line, and the problem will resolve itself.
See if you follow everything, and then let me know.
Cheers
Wizard