If wali of girl is not agreed for marriage, what is available way to perform Nikkah other than court marriage?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If the guardian's disapproval was due to a legitimate reason such as when the proposer is incompetent (inadequate in his religion and morals), then in this case, it is his right, and the woman has no right to oblige him to agree to the incompetent one. The scholars have stated that the right in the competence is for both the guardian and the woman, and neither of them has the right to independently decide in accepting someone who is incompetent. But if the guardian’s refusal was illegitimate, but rather due to his stubbornness, then, in this case, he commits a sin and has no right to refuse. In this case, the guardianship is transferred from him to the closest of her guardians after him, or the matter is referred to the court.

In conclusion, there is no way for a woman to marry according to Sharee'ah except through the guardian or the judge.

Allah knows best.