As Roadmap rolled out we also added a new control to allow administrators to enable Roadmap for their users. Now we are almost complete with that rollout we are planning a change that will see Roadmap enabled by default in the Office 365 Admin Center, so that users will not need to wait for your organization's administrator to enable it. To learn more about Roadmap if you haven't tried it yet take a tour at the Welcome to Roadmap video
We will respect the 'off' state if a customer has chosen to disable Roadmap - so all you need to do before March 16th 2019 is to navigate to the page above and hit 'Save' - and then we will not enable it. If you had previously turned on and off again, then also go to the page and hit 'Save' again, just to be sure we know you should stay 'off'. See https://docs.microsoft.com/en-us/projectonline/turn-roadmap-on-or-off for more details on getting to that setting.