killall pingshould work.
pingas a background job because you used & at the end.
ping -i 10 220.127.116.11 &
ping -i 10 18.104.22.168 &again and type
fgagin, but don't hit ctrl+c now but instead hit ctrl+z
bgor make it running in foregound by typing
jobsthe  indicates ping is job number 1 and it will show it's current state also.
kill %1and it's gone,
jobsand pick up exactly where you left by