It may be time consuming to get all the application Ids from YARN and kill them one by one. You can use a Bash for loop to accomplish this repetitive task quickly and more efficiently as shown below:
Kill all applications on YARN which are in ACCEPTED state:
for x in $(yarn application -list -appStates ACCEPTED | awk 'NR > 2 { print $1 }'); do yarn application -kill $x; done
Kill all applications on YARN which are in RUNNING state:
for x in $(yarn application -list -appStates RUNNING | awk 'NR > 2 { print $1 }'); do yarn application -kill $x; done