Fitter is assigning pins according to the old pin plan

Hi,
I have two FPGA designs for two different FPGAs(in Quartus).
I did one project for one FPGA and then then copied the same project and modified it according to second FPGA.
Now, I also changed the pin assignments in pin planner. But when I compiled the design, fitter is picking up pins according to both new and old i.e. the pins which are unassigned in new design are getting pin assignments from old design.

I tried to remove old Fitter assignments through Remove Assignments, but as soon as I re-compile design, old assignments appear in the pin planner.

I also deleted db and incremental_db. No use.

And if I download the same design on FPGA, my board my get burned.

So guys, what to do? I am running Quartus 16.1.2 Lite.