Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Answering your question, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
You are required to shave or trim your hair to achieve the release from ihram.
If the machine or scissors remove the hair wholly, then it is reckoned as shaving and fine. If, however, they only trim or cut the hair without removing them altogether, then it is sufficient to fulfill the requirement of trimming or cutting.
After having said this, it is always best, in the case of doubt, to follow the safest.
Almighty Allah knows best.