A developer is delaying my project despite him telling me that the project will be delivered on a certain date, can I terminate the work and move it on to another reliable developer>

You're entitled to end a working relationship with a freelancer however keep in mind that if the developer spent time working on the project he/she will more than likely request a partial payment. It's only fair if they already started on the project and have the base of it done. Just make sure to ask for any files they created so you have copies of them for when the next developer takes over.

In order to end the working relationship, you need to contact the freelancer and notify them that you no longer wish to work with them. Offer them a settlement payment if they did work on the project and if nothing was done then request a full refund.