Can You Repent without Wudu or Ghusl?
Question

I would like to know if performing the washing (that is performed before prayer and reading the Quran not ghsul) is necessary before performing tawbah (confessing and being sorry for your sins). And also if ghsul is necessary before tawbah in the case that someone is unclean.
Praise be to Allah.Every son of Adam commits sin
There is no human being who does not commit sin, and the best of them are those who hasten to repent. It was narrated from Anas that the Prophet (peace and blessings of Allah be upon him) said: “Every son of Adam commits sin and the best of those who commit sin are those who repent.” (Narrated by At-Tirmidhi, 2499; Ibn Majah, 4251; classed as good by Al-Albani in Sahih Al-Jami`, 3428. 
Allah has enjoined repentance upon His slaves
Allah has enjoined repentance upon His slaves , as He says (interpretation of the meaning): 
“O you who believe! Turn to Allah with sincere repentance! It may be that your Lord will expiate from you your sins, and admit you into Gardens under which rivers flow (Paradise)” [At-Tahrim 66:8]
Will Allah accept your repentance?
And Allah has told us that He accepts the repentance of His slaves and forgives them; indeed He turns their bad deeds into good deeds. Allah says (interpretation of the meaning): 
“And He it is Who accepts repentance from His slaves, and forgives sins, and He knows what you do.” [Ash-Shura 42:25] 
“Except those who repent and believe (in Islamic Monotheism), and do righteous deeds; for those, Allah will change their sins into good deeds, and Allah is Oft-Forgiving, Most Merciful.” [Al-Furqan 25:70]
Can you repent without Wudu or Ghusl?
Allah has not commanded the person who repents to do Wudu or Ghusl, whether his impurity is minor or major, either before or after repenting, unless he is repenting from disbelief or apostasy. 
The scholars of the Standing Committee said: 
“Ghusl is not required after sincere repentance from sin, because the basic principle is that it is not prescribed, and we do not know of any evidence that differs from this principle except if the person is repenting from disbelief, because it is prescribed for the one who enters Islam to do Ghusl, because the Prophet (peace and blessings of Allah be upon him) commanded Qays ibn `Asim to do that when he became Muslim. (Narrated by Imam Ahmad, Abu Dawud, At-Tirmidhi and An-Nasa’i; classed as authentic by Ibn As-Sakan) ( Fatawa Al-Lajnah Ad-Da’imah, 5/317)
Conditions of repentance in Islam
The conditions of repentance according to the scholars are well known; they do not include Wudu or Ghusl. These conditions are as follows: 

Sincerity in repentance .
Giving up the sin.
Regretting the sin.
Resolving not to go back to the sin.
Repenting at the time when repentance is accepted, for Allah does not accept repentance once the death rattle reaches the throat when the soul is being taken, or after the sun rises from the west.
Restoring rights to people if the sin had to do with transgressions against the rights of other people.

And Allah knows best.