You can use following command to get only pid:

sudo netstat -peanut | grep 3000 | awk '{ print $9 }' | sed 's:/[^/]*$::' | grep -Eo '[0-9]{1,5}'
awk command gets the 9-th field.

sed command gets the pid before forward slash.

And grep command returns only numbers to eliminate extra lines.

Here you can simply have a loop and kill processes.

https://stackoverflow.com/questions/37971961/docker-error-bind-address-already-in-use