The answer to your question is Urban Development and Housing Act of 1992.
There is a provision there about the power of local government units to remove squatters.
URBAN RENEWAL AND RESETTLEMENT
Sec. 26. Urban Renewal and Resettlement. — This shall include the rehabilitation and development of blighted and slum areas and the resettlement of Program beneficiaries in accordance with the provisions of this Act. On-site development shall be implemented whenever possible in order to ensure minimum resettlement of the beneficiaries of the Program from their existing places of occupancy shall be undertaken only when on-site development is not feasible and after compliance with the procedures laid down in Section 28 of this Act.
Sec. 27. Action Against Professional Squatters and Squatting Syndicates. — The local government units, in cooperation with the Philippine National Police, the Presidential Commission for the Urban Poor (PCUP), and the PCUP-accredited urban poor organization in the area, shall adopt measures to identify and effectively curtail the nefarious and illegal activities of professional squatters and squatting syndicates, as herein defined.chanrobles virtual law library
Any person or group identified as such shall be summarily evicted and their dwellings or structures demolished, and shall be disqualified to avail of the benefits of the Program. A public official who tolerates or abets the commission of the abovementioned acts shall be dealt with in accordance with existing laws.chanrobles virtual law library
For purposes of this Act, professional squatters or members of squatting syndicates shall be imposed the penalty of six (6) years imprisonment of a fine of not less than Sixty thousand pesos (P60,000.00) but not more than One hundred thousand pesos (P100,000), or both, at the discretion of the court.cralaw
Sec. 28. Eviction and Demolition. — Eviction or demolition as a practice shall be discouraged. Eviction or demolition, however, may be allowed under the following situations:
(a) When persons or entities occupy danger areas such as esteros, railroad tracks, garbage dumps, riverbanks, shorelines, waterways, and other public places such as sidewalks, roads, parks, and playgrounds;
(b) When government infrastructure projects with available funding are about to be implemented; or
(c) When there is a court order for eviction and demolition.
In the execution of eviction or demolition orders involving underprivileged and homeless citizens, the following shall be mandatory:
(1) Notice upon the effected persons or entities at least thirty (30) days prior to the date of eviction or demolition;
(2) Adequate consultations on the matter of settlement with the duly designated representatives of the families to be resettled and the affected communities in the areas where they are to be relocated;
(3) Presence of local government officials or their representatives during eviction or demolition;
(4) Proper identification of all persons taking part in the demolition;
(5) Execution of eviction or demolition only during regular office hours from Mondays to Fridays and during good weather, unless the affected families consent otherwise;
(6) No use of heavy equipment for demolition except for structures that are permanent and of concrete materials;
(7) Proper uniforms for members of the Philippine National Police who shall occupy the first line of law enforcement and observe proper disturbance control procedures; and
Adequate relocation, whether temporary or permanent: Provided, however, That in cases of eviction and demolition pursuant to a court order involving underprivileged and homeless citizens, relocation shall be undertaken by the local government unit concerned and the National Housing Authority with the assistance of other government agencies within forty-five (45) days from service of notice of final judgment by the court, after which period the said order shall be executed: Provided, further, That should relocation not be possible within the said period, financial assistance in the amount equivalent to the prevailing minimum daily wage multiplied by sixty (60) days shall be extended to the affected families by the local government unit concerned.
This Department of the Interior and Local Government and the Housing and Urban Development Coordinating Council shall jointly promulgate the necessary rules and regulations to carry out the above provision.