I have to use a sensor and one of the steps asked me to delete the parameter that references the UART serial port (ttyAMA0) in cmdline.txt, does it mean that I have to delete this part console=serial0,115200 from my cmdline.txt :
dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=/dev/mmcblk0p7 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait
one of the steps asked me to delete the parameter that references the UART serial port (ttyAMA0) in cmdline.txt, does it mean that I have to delete this part console=serial0,115200 from my cmdline.txt
Yes. This is to stop the kernel from using that for console output (boot and warning/error messages).
Make sure that file remains all one line. Parameters should be separated by spaces, but key/value pairs should not contain any (i.e., key=value, not key = value).
You could delete serial0 BUT the preferable way to manage changes is through raspi-config. This just modifies the same files, but does it in a standard way across different models.
You don't say which model you are using, or which sensor. Presumably this uses serial, so you may have to modify any code which accesses it. Also the serial port is disabled by default on the Pi3. See How-do-i-make-serial-work-on-the-raspberry-pi3
