NVM, got it working with this (might look messy, but at least it works):
// =======================================
// Remove deleted rows
var deleteThisCodaRows = [];
const regexRowID = /[^\/]*$/;
allRows['sourceRows'].map(function(row) {
rowLink = row['cells'].slice(-1)[0]['value'];
deleteThisCodaRows.push(regexRowID.exec(rowLink)[0].slice(3))
})
var body = {
'rowIds': deleteThisCodaRows,
};
CodaAPI.deleteRows(SOURCE_DOC_ID, SOURCE_TABLE_ID, body);
// =======================================