Hi @margs333,
The first thing you should do before considering any kind of demolition work is confirm that these tiles do not contain any asbestos. It is always better to be safe than sorry when it comes to asbestos, so please contact an asbestos testing company before proceeding.
If it is found to be an asbestos-containing material, you will need to get the assistance of asbestos removal specialists.
If it is found to not contain asbestos, the process will involve finding a weak point, possibly a seam between pieces, or around the edges of the ceiling and using a Pry Bar to begin levering one off. Once you have access to the top edge of a panel, you can switch over to something like this Carinya 1.2m x 150mm Floor Scraper which can be used to get under the top edge and lever the panels off. The process will be messy and quite destructive, so don't be concerned if you damage things in the process as it will need to be reinstated anyway.
The most important thing is to ensure you are being safe, so please have it tested before you proceed.
Let me know if you have any further questions.
Jacob
