>> set your variables:
TOKEN=""
REGION="lon"
DDI=""  < this is the account number

>> Generate a list of backup agents
curl -sH  "X-Auth-Token: $TOKEN" -H "Content-type: application/json" -X GET https://$REGION.backup.api.rackspacecloud.com/v1.0/$DDI/user/agents | python -m json.tool | egrep "MachineName|MachineAgentId" | awk -F":" '{print $2}' | sed 's/ //g' | sed '{N;s/\n//}' > list.txt

>> Manually remove WANTED backup agents (leave only the ones you want to remove):
vim list.txt 

>> Generate remove list
awk -F, '{print $1}' list.txt > remove.txt


>> generate the exec file to review
for AGENTID in `cat remove.txt`; do echo curl -sH \"X-Auth-Token: $TOKEN\" -H \"Content-type: application/json\" -X POST https://$REGION.backup.api.rackspacecloud.com/v1.0/$DDI/agent/delete -d \'{\"MachineAgentId\": $AGENTID}\' ; done >> exec_me

>> exec the API calls
/bin/bash exec_me