CC Ādi 5.105

rudra-rūpa dhari’ kare jagat saṁhāra
sṛṣṭi-sthiti-pralaya — icchāya yāṅhāra
rudra-rūpa — the form of Lord Śiva; dhari’ — accepting; kare — does; jagat saṁhāra — annihilation of the material world; sṛṣṭi-sthiti-pralaya — creation, maintenance and annihilation; icchāya — by the will; yāṅhāra — of whom.
Assuming the form of Rudra, He destroys the creation. Thus creation, maintenance and dissolution are created by His will.

Maheśvara, or Lord Śiva, is not an ordinary living being, nor is he equal to Lord Viṣṇu. Effectively comparing Lord Viṣṇu and Lord Śiva, the Brahma-saṁhitā says that Viṣṇu is like milk, whereas Śiva is like yogurt. Yogurt is nothing like milk, but nevertheless it is milk also.