Ask a lawyer to prepare a Deed of Extra-Judicial Settlement of Estate. All the heirs will sign the Deed. Once executed and notarized, you will submit the Deed together with other required documents with the BIR. (Check BIR website for list of documents needed). Once the tax is assessed, you will pay the estate tax due with any authorized agent bank of the BIR. Once paid, the BIR will issue a Tax Clearance and Certification Authorizing Registration (CAR).
You will also pay the transfer tax with the local government where the property is located.
There is also a need to publish in a newspaper for 3 consecutive weeks the notice of extra-judicial settlement of estate. After publication, secure an Affidavit of Publication and the Newspaper(s) where the notice was published.
These are the requirements you need to comply with before proceeding to the Register of Deeds (RD) to transfer the title of the real property in the name of the heirs of the decedent.
Note that the estate tax will incur penalty if not settled within the prescribed period (6 months from death of decedent if I remember it right).