Ifyou are the only one on lease and you ask other person to leave, do you have to evict them?

Was this person supposed to have paid rent or were they a long-term guest (i.e. were they there for more than 30 days). If your answer is "no", then they were merely a guest and can be immediately put out. If, however, the answer is "yes" then you will have to go through a formal eviction process. This starts by giving your occupant 30 days notice to vacate. If they do not move out by the date given, then you will have to go to court and file an "unlawful detainer" action. Once the court rules in your favor the judge will issue an order to vacate. If your occupant still fails to leave then you can have the sheriff come and remove them.  

In the meantime do not undertake any "self-help" measures such as changing the locks, etc.  This will work against you.  What you should do now is to contact a tenant's right organization or real estate attorney.  They can advise you of the correct way in which to go about this.

Note: Typically the person who is named on the lease has the right to put an unnamed occupant out. However, if this occupant is a legally recognized tenant, then only the landlord can file for the eviction.  And you should be aware that having a person's name on a lease is not the only way that they may be considered to be a legal tenant.  In addition to being on the lease, they may have achieved the status of a tenant if your landlord accepted rent from them directly.  Also, if the landlord put (or allowed them to put) their name on the mailbox/doorbell, and/or if you and they rented the place together and it was clear that you were both on equal footing.