I was a part owner in a home with my parents which sold in Mar 2015.I am now buying a home in April 2019. Can I withdraw from my RRSP under the home buyers plan?

Here is a CRA page with info on eligibility for the Home Buyers' Plan (HBP): https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/rrsps-related-plans/what-home-buyers-plan/participate-home-buyers-plan.html

If you have more questions on whether you are eligible, you can contact the CRA. If you are in Canada or the United States, you can call the CRA at 1-800-959-8281. If you are somewhere else you can call 613-940-8495. Here are more ways to contact the CRA: https://www.canada.ca/en/revenue-agency/corporate/contact-information/telephone-numbers.html