hide somebody's identity
conceal somebody's identity

If a friend, why did she try to conceal her identity?

Each of them make a radio name to conceal their identity.

That was why he had to conceal his identity; the less known about him, the better.

It also did not hurt to conceal his true identity.

In order to conceal their own identity, they use the bank details of others.

There was little hope of concealing his identity, but he had to try.

Lots of people had good reason to conceal their identities.

Why had someone been at pains to conceal her identity?

Or probably just to conceal their identities while they bought drugs.

Why should I try to conceal my identity from you?