When there is a lock icon next to one of your contact's name it means that they have chosen to not share their presence state with other users.
To no longer share your presence with others, do the following from one of your clients. Change it on one device and the setting will be reflected on all your devices!
View the Amazon Chime User, Administration Guide and API Reference on the AWS Documentation site.
Find more information about the Amazon Chime solution, pricing, customer references, getting started, and other resources.