Kindly refer to the following links:

Whats the ruling of a marriage with no wali?  (website)


A woman's marriage without the consent of her wali (guardian) 


Does a divorced woman need consent of her guardian (Wali) to marry for a second time


If the guardian rejected many potential suitors, who were good, then the woman has the right to approach the Muslim court so that they would appoint another guardian for her 


Can my brother be my wali / guardian if my father rejects the guy I want to marry? 


How can a  woman get Married if her Wali is in another country? | Sheikh Assim Al Hakeem


Can a father who does not pray be the wali (guardian) for his daughter's marriage?

Hanafi

Marriage without the consent of the woman's wali - Hanafi Madhab


Is marriage invalid if the bride's father (wali) didn't propose to the Groom during the nikah? How to fix this? (Hanafi Madhab)


If Imam conducts the Nikkah instead of the father, is the marriage valid? ijab and qubool


I married my wife without her father's consent, is our marriage valid (local fatwa)


what if the woman wants to get a divorce, can she just leave the marriage as it is not a valid marriage?

They need to go the authorized Islamic center or their local Islamic judge to solve this issue.

If she went into the marriage believing that it is a valid marriage, she can’t just walk away from it just like that. 


Marriage behind parent's back 


A woman married without her father's consent, left her "husband", can she remarry?



Answer:


The Prophet ﷺ ruled that any marriage that takes place without the consent of the guardian (Wali) is void.

















And Allah Knows Best