Welcome to HCM.
You haven't mentioned your age and about your sexual activity.
Moreover are you a diabetic or not?
Do you have your foreskin intact or not? Is it easily retractable or not? These questions are relevant to your problem.
Itching over the tip of the penis can occur due to many reasons like tight foreskin, not able to clean well, soap particles left over, smegma
, Insect bite etc. apart from certain infections like yeast, Scabies(itch mite) etc.
If you can answer the questions above I may be able to tell more solutions for your problem.
It is better for you to consult a Dermatologist
if the problem persists. Otherwise a better cleanliness with ordinary water is sufficient.