Is Trimming the Beard Haram?
Question

I have a question about the beard. I know that the beard should be left alone and not trimmed.  But there are some people who let their beard grow and they look scary. Our imam told us that it is not sunnah to let the beard grow so long that the faces look scary. Some men only have goatee, hair on their upper lip and chin and they are ‘alims and imams. Can you please help me on this subject?
Praise be to Allah.Is it haram to trim the beard?
The Sunnah of the Messenger of Allah (peace and blessings of Allah be upon him) indicates that it is obligatory to let the beard grow and that it is haram to shave it or cut it . 
The Prophet (peace and blessings of Allah be upon him) said: “Cut the moustache and let the beard grow; be different from the unbelievers.” (al-Bukhari, al-Libas, 5442; Muslim, al-Taharah, 382) 
There are many hadiths which say the same as this hadith, indicating that it is obligatory to leave the beard alone and let it grow and that it is haram to shave it or cut it .
Whoever claims that letting the beard grow is no more than a Sunnah for which a person may be rewarded and the one who does not do it will not be punished is going against the sound hadiths. 
Did the Prophet trim his beard?
The report that says that the Prophet (peace and blessings of Allah be upon him) used to trim the length and breadth of his beard is a false hadith.
Islam is the religion of beauty
But it should be noted that Islam is the religion of beauty, as it was narrated in the hadith, “[A man said,] ‘What if a man likes his clothes and his shoes to look good?’ The Prophet (peace and blessings of Allah be upon him) said, ‘Allah is Beautiful and loves beauty.’” (Narrated by Muslim, al-Iman, 131)
 The Prophet (peace and blessings of Allah be upon him) commanded [one of his Companions] to change gray hair , when he said, “Change this gray hair, but avoid black.” (Narrated by Muslim, Kitab al-Libas wa’l-Zinah, 2102)
The Prophet (peace and blessings of Allah be upon him) recommended combing hair, and said, “Whoever has hair, let him take care of it.” (Abu Dawud, Kitab al-Tarajjul, 3632. Al-Albani said in Sahih Sunan Abi Dawud: it is hasan sahih. Hadith no. 3509)
Al-Hafiz Ibn Hajar said: “Ibn Battal said: combing means tidying the hair of the head and beard, and oiling it.” This is the Sunnah of the Prophet (peace and blessings of Allah be upon him), and he (peace and blessings of Allah be upon him) said, “Whoever turns away from my Sunnah has nothing to do with me.” (Narrated by al-Bukhari, al-Nikah, 4675) 
Unwanted beautification 
The beauty referred to is shar’i or Islamic beauty (beauty as prescribed in Islam), and not the so-called beauty which appeals to sick minds which are enamoured of non-Muslim fashions and the appearance of corrupt people such as male and female actors and singers, or fashion models. 
Hence when some people were misled by those immoral western women who pluck or shave or draw their eyebrows , or make their nails long, or have tattoos, and thought that this is beauty, many Muslim women imitated them in these things, even though they are forbidden by shari’ah. 
The point is not what is fashionable in the east or the west, the point is the shari’ah which advocates wearing perfume (for men), keeping clean, dressing nicely, combing the hair, changing gray hair, and other kinds of beautification which are prescribed in Islam. 
And Allah is the Source of strength.