She wants to cut off all desire and never get married

Praise
be to Allah.

Firstly: 

Allah, may He be exalted, has created sexual desire in humans because of the
great benefits that result from it. 

The Prophet (blessings and peace of Allah be upon him) forbade castration
and celibacy that deprive a person of permissible pleasure. The scholars
drew an analogy between that and everything that leads to prevention of
desire and producing offspring altogether. 

As-San‘aani (may Allah have mercy on him) said: 

…
They were unanimously agreed that cutting of the penis and castration are
prohibited, and they included with that anything that comes under the same
heading.

End quote from Subul as-Salaam (2/160) 

Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allah have mercy on him) was asked: is
it permissible for a man take medication in order to reduce sexual desire? 

He
replied:

There is nothing wrong with that, but it is not permissible for him to take
any medication that will stop it permanently. As for reducing it, there is
nothing wrong with that, because that serves an obvious purpose. The
Messenger of Allah (blessings and peace of Allah be upon him) stated that
fasting reduces desire, in the hadith in which he (blessings and peace of
Allah be upon him) said: “O young men, whoever among you can afford it, let
him get married, for it is more effective in lowering the gaze and guarding
one’s chastity. And whoever cannot afford it, let him fast, for it will be a
shield for him.”

End quote from Majmoo‘ Fataawa Ibn Baaz (21/188) 

See also questions no. 126987 and
127165 

Removing the clitoris altogether is not permissible, because it weakens
desire severely or takes it away altogether. Rather what is prescribed in
this regard is to cut a small part of it so as to moderate desire. This is
the teaching of the Messenger (blessings and peace of Allah be upon him), as
has been explained in the answer to question no. 9412. 

With regard to your resolve never to get married at all, this is
inappropriate because the ruling on marriage – for young people – is that it
is either obligatory or recommended, and it is an act of obedience to Allah,
may He be exalted, according to either opinion. Some of the scholars
regarded it as an obligatory act of obedience, and others regard it as
encouraged but not obligatory, but it is obligatory in the case of one who
is overwhelmed by desire and fears hardship or falling into that which is
haraam, as appears to be the case in your situation. We have explained this
in the answer to question no. 220841 

Marriage leads to many benefits and good things that are missed out on by
the one who does not get married. Hence marriage was the practice of the
Messengers. Allah, may He be exalted, says (interpretation of the meaning):
“And indeed We sent Messengers before you (O
Muhammad blessings and peace of Allah be upon him), and made for them wives
and offspring” [ar-Ra‘d
13:38]. 

You may think that the time is not right to take this decision (concerning
marriage), but it will be appropriate at the right time, in sha Allah. It is
sufficient that it will protect you from this sin that you are doing, namely
masturbation, and this is the prescribed remedy for this sin, not what you
want to do. Hence the Prophet (blessings and peace of Allah be upon him)
instructed young people to get married, and he said: “…it is more effective
in lowering the gaze and guarding one’s chastity.” Narrated by al-Bukhaari
(5065) and Muslim (1400). 

Our advice to you is to accept the idea of marriage, now and not at some
other time, and to seek reward in it by means of good intentions, such as
maintaining chastity, obeying the husband and raising children, and so on. 

We
ask Allah, may He be exalted, to enable you to do all that is good. 

And Allah knows best.