How do you hide your past online identity when you enter Academia?
Firstly look into the possibility of changing your YouTube name. If this is not possible, see if you can create a new YT account and move the videos into this.
Whatever about YouTube, your academic name is better being different to your commonly used name: we are all entitled to a life away from our work and from any &quot;reputation&quot; that follows from this. How best to select your academic name depends on:

The country you are in

The commonness of your first name, middle name(s) and surname

Naming conventions in your country


So, for example, if your YouTube name is Pablo Garcia, your middle name is Enrique and your mother's name is Sota you might publish under the name P.E. Garcia Sota. Likewise if you live in Netherlands and your YouTube name is Johan Van Dijk, you might, if your middle name is Willem, publish under J.W.V. Dyck as the latter form is often used in English publications. English native-speakers might use a number of first name initials and maybe omit the usual one if it is unusual enough to be searchable. Irish people have the legal option of using the Gaelic version of their name. Doubtless there are other possibilities in other countries, there may even be regional naming conventions in parts of France and Germany.
Look into the options in your own country and then do some trial searches on the main engines. Be careful to avoid a name that already has an existing big persona attached to it, especially in academia, as Google searches will associate you with them. Use Google Scholar to help with this.
Discuss your final selections with those close to you.