plugin ucan post adds 3943 to home page url and redirects to unfound page

Hello

Please help.
wwww.goodbyetv.com uses a lysa theme and a number of plugins. Today I added ucan post and followed the instructions to type the code into a Page.

At first the Page appeared as a form on the Home Page so I uninstalled it.

The home page https://www.goodbyetv.com redirected to https://www.goodbyetv.com/3943 Page not Found.
I cleared the cache – and waited. Still the same redirect. I tried using the redirect plugin to redirect the error page back to the rela homepage – even worse it identified 301 direct but the home page would not load (never going to complete message) at all! I took off the redirect.
As the problem was still there I reinstalled the ucan post plugin calling the page Submit YOUR Rant. The https://www.goodbyetv.com home page is STILL redirecting!!!
I uninstalled – tried to add as text box -problem with home page remains. I reinstalled as page and have left it up – please have a look at it. Please be kind and slow with your advice about how to resolve this. I can pack and unpack plugins and cut and paste code if told exactly where to put it but know nothing about code.