There should be a command on terminal that hides the history belongs a specific tab and lets you start from the beginning of the tab like it is new, but when you scroll up with a mouse you can see your history. I can't remember and find it online. I hope someone can tell it.
If you want to clear your terminal window:
- use the command
clearto clear whatever is showing
command+Kto clear everything
There are other things you can try too: https://stackoverflow.com/questions/2198377/how-to-clear-previous-output-in-terminal-in-mac-os-x