I have tried some ways writing client script but it didn’t work.
if (frm.doc.table_hnlr.length > 0) {
cur_frm.fields_dict['table_hnlr'][0].cannot_delete_rows = 1;
}
Another one
cur_frm.set_df_property('table_hnlr', 'cannot_delete_rows', 1);
if (childTable.length > 1) {
for (var i = 1; i < childTable.length; i++) {
cur_frm.fields_dict['table_hnlr'][i].cannot_delete_rows = 0;
}
}