The info on the page Troubleshooting Repository Size helped us find the semi-documented Repository API call that enables push force for the entire repo. I made a bash script compatible with Git For Windows Credentials Helper that does just that. You can put it into /usr/bin/ and call from any Git Bash session:
#!/bin/bash
#
#
set -e
set -o pipefail
url=$(git config --get-regexp "^remote\..*\.url$" | sed 's,.*\(https://git.api.mendix.com/.*\),\1,;t;d')
MENDIX_TOKEN=$(echo "url=${url:?}" | git credential fill | sed 's,^password=,,;t;d')
appid=$(echo "${url:?}" | sed 's,https://git.api.mendix.com/\(.*\)\..*,\1,;t;d')
echo connecting to repository api...
curl -s -v "https://repository.api.mendix.com/v1/repositories/${appid:?}/enable-force-push" \
--header "Authorization: MxToken ${MENDIX_TOKEN:?}" \
--data '' 2>&1 | sed 's/\(.*uthorization:\).*/\1 _omitted_/'