Originally Posted by
a77impala
That looks like the bearing cup, not the headtube. Drift it out and replace it.
No I don't think it's a head cup, but now I looked closer and it might be a integrated headset. That changes everything, in someways making it easier, in others harder. if it is an integrated headset, the outer lip is meaning less, so you just have to gently tap it back to where the bearing can drop in past it. That's the easy part, the hard part is that the conical bearing seat might be affected, so you'll have to see a mechanic and have it re-cut with the proper mill.
Given that you'll need a pro to finish the job anyway, I suggest you find a qualified shop and let them do the whole job.
summary, thin wall with press-in headset is DIY, integrated is a job f0r a pro. Fairly straightforward either way.