Yes, you can share you CloudFit login with your with your trainers.
That means they will have full access to create/run/stop workouts on your account.
Please note that there is some risk with using CloudFit in this manner as it increases the chance that someone might accidentally delete things or stop workout before its meant to finish. We highly recommend that you educate your trainers on how to use CloudFit before allowing them access as we are unable to control what they do.
If you run multiple sites and have more complex needs with regards to controls and restricting user access please get in touch with our support team firstname.lastname@example.org to arrange a call with our Enterprise Services team.