This article shows you how to stop sharing your last seen time and online status on Telegram. Note that once you hide your last seen time and online status, you won’t be able to see this stuff of other people.
1. Tap the hamburger icon in the top left corner to open the drawer menu then select Settings:
2. Go to Privacy and Security:
3. Navigate to Last Seen & Online:
4. Select Nobody as the screenshot below:
You can still share your online status with some specific people. Head to the Add exceptions section and tap Add Users then select one or many of your friends from the list.