This has been mentioned a few times in other threads but not straight out as a bug report that I can tell.
If creating a Custom Channels source, if you remove that source, and later create a new Custom Channels source with the same name, some of the first setup bleeds through to the new source. This is repeatable. It is also a reason why some of us here when helping people with custom channels problems always tell people to use a new source name.
In this test I used Frndly as I am very familiar with how to set it up. In reconfirming this issue I created a Custom Channels source named tagme. I used a Frndly source URL and for XMLTV the Frndly http://host:8183/playlist.m3u8?gracenote=include. It setup properly with no problems. I remove the tagme source. I then add a source again, still called tagme. This time I use a text source for accuweather and I do not provide an xmltv link. When going to edit settings it shows the text source data but the xmltv link (which I left empty) is now filled in with the Frndly link I used in the original. I remove the xmltv link, leave blank and hit save. I go back to edit setting and the Frndly link is still there. So I remove the tagme source again. Just to confirm it is not the computer or the browser, I go to a completely different computer, using a different OS, using a different browser. I setup another source still called tagme. I do another text source and leave the xmltv link blank. I go to edit settings. The xmltv link data is filled in again with the Frndly link even though no link was provided, it is a completely different computer, different OS and a different browser.
Anyway, this has been going on for as long as I can remember. I know some others have experience this issue too. Just wanted to make a formal bug report on it and outline the steps I used to reproduce.