I had similar problems at one point, the solution I came up with was a bit of a kludge - I'm sure there's a more elegant way to tell the router not to use dnscrypt-proxy - but it worked. I'm pretty certain this is what I did, but it was a while ago now so apologies in advance if doesn't work:
I downloaded the
raw installer script from github on my phone (path as above), copied it from the phone to my PC over USB, then uploaded it from the PC to the router's /jffs/scripts folder via WinSCP. Marked it as executable then ran the installer via ssh:
Code:
sh /jffs/scripts/installer
I think this would enable you to uninstall.