About two months ago I pulled a hair from penis shaft and now a red bump has formed, it doesn't hurt but is very visible. How can I treat it?

May just wait... The red bump may be still the healing scarring effect after pulling that hair out, which could be related with its corresponding sebaceous gland. If not hurting and not changing in its size, may just watch and see. Of course, it is hard to give right diagnosis for right care without a direct look at & feel on it. If still in doubt, seek evaluation and counseling timely as needed.