In your documentation
Abaout Section ->Step3. Go to Dashboard >> Appearance >> Customize >> About section >> About Section
Add Contact Phone Tagline & Phone No. Or Background Image
set contact section
there is an explanation of how to change or remove the phone , which is 1800-12-4567 and text – Call now”,
But that option option does not exist.
It is not possible to change or remove that phone number and text.