Hi, thanks for your question. Just a bit more information required to fully assist you:
-Are you in England or Wales?
-Are there any formal agreements or deeds of trust regarding the property?
-Do you have any children together, if so how old and what are the proposed arrangements?
My name is ***** ***** I have been a family lawyer for more than 30 years.
Since you are the sole owner of the property then technically you can give your partner "reasonable written notice to leave" (given the circumstances at least two months) and at the end of that time change the locks.
However you would be unwise to do so given the fact that you have a child together.
This is because if your ex seeks legal advice she will be told that under Schedule 1 of the Children Act she could potentially apply for an Order allowing her to remain in the property with the child and forcing you to leave.
It is not certain that she would be successful as it depends on the value of the property and the outstanding mortgage and the price of two bedroom properties in the area.
It would be sensible to try and discuss matters with her using Family mediation - since she will walk away with nothing when the child is 18 (or if she cohabits) if she stays in your property a lump sum which allows her to establish herself away may be attractive to her
Please ask if you need further details
You are most welcome I hope all goes well