1 Timothy 4 King James Version (KJV)

1, Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils;

2, Speaking lies in hypocrisy; having their conscience seared with a hot iron;

3, Forbidding to marry, and commanding to abstain from meats, which God hath created to be received with thanksgiving of them which believe and know the truth.

4, For every creature of God is good, and nothing to be refused, if it be received with thanksgiving:

for not wanting to marry is it a sin? as the verse clearly stated?

If you Dont want a wife, its not a sin so far you can keep yourself from immorality, but if you know you can't, the Bible compel/advice us to get married to avoid stories that touches the heart, also the benefit of getting married outweighs that of staying single all your life.
Forbidding to get married is more of doctrines, which the Holy spirit condemn, that you want to give yourself to God shouldn't be collective but individual, if you don't want a wife and you're sure by the grace of God you wont fall into sin, fine, go ahead, you've not commit sin, but know that you shortchanged yourself of so many of God's blessings : Reproduction, Blessings, fruitfulness and multiplication and many more.
Hope I was able to answer right, if not kindly point it out.
Shalom.

@joel3, you just have to use different version of the Bible to get the point there. That part was referring to ministers who bring in strange and false doctrines into Christendom.

New International Version
They forbid people to marry and order them to abstain from certain foods, which God created to be received with thanksgiving by those who believe and who know the truth.


New Living Translation
They will say it is wrong to be married and wrong to eat certain foods. But God created those foods to be eaten with thanks by faithful people who know the truth.


English Standard Version


who forbid marriage and require abstinence from foods that God created to be received with thanksgiving by those who believe and know the truth.