Their inhibition is by practice and detachment
Flowing both ways, the so-called stream of the mind flows to good or flows to evil. When it is borne on to release, down into the field of discrimination, that is the flow towards good: when it is borne on to saṃsāra, down into the field of failure to discriminate, that is the evil flow. By detachment the current towards objects is dammed, and by practice of discriminating vision the auspicious current of discrimination is made to flow. Thus inhibition of the mental process depends on both.
He explains the means for their inhibition: Their inhibition is by practice and detachment. The characteristics of practice and detachment will be described in the coming sūtra-s. By these two the mental processes already described are inhibited, because they are opposed to them. Inhibition (nirodha) means cessation (upaśama). To show discrimination as the object of practice and detachment, the commentary explains the mind-stream.
The men of saṃsāra are always carried by the mind, as by a stream, towards objects. They are borne on to saṃsāra, ending up in saṃsāra, which is like an ocean, dammed up: held back, made to flow: set in movement, by making an opening. The form udghāṭyate is an optional retention of the long vowel in the causative, which otherwise would be short according to the Pāṇini sūtra 6.4.92.
So it depends on both, it is dependent on both practice and detachment.