Leaver that hasn†t been paid in this tax year

SOLVED
Hello. We have some employees on the payroll that did not work at all in this tax year and we would like to make them leavers before Year End. What would be the best method? And what date should I put on the P45 as I do not know when was their last day of work in the previous tax year. Also, some employees worked for us in June 2016 but havenâ€Tmt work since then. Weâ€Tmve paid the holiday pay due to them in November. Now I want to make them leavers, what date should I use on the P45? Should I use June, November or current processing date? Thank you, Adriana