Swami Vivekananda was one of the greatest reformers of Hindu religion. While he strongly upheld the greatness of Hinduism and protected it against all missionary influences, he was brave enough to concede that Hinduism needs a cleansing especially of its superstitions and evil practices.  He said in his lecture in Madras,

We must not forget that what I mean by the conquest of the world by spiritual thought is the sending out of the life-giving principles, not the hundreds of superstitions that we have been hugging to our breasts for centuries. These have to be weeded out even on this soil, and thrown aside, so that they may die for ever. These are the causes of the degradation of the race and will lead to softening of the brain. That brain which cannot think high and noble thoughts, which has lost all power of originality, which has lost all vigour, that brain which is always poisoning itself with all sorts of little superstitions passing under the name of religion, we must beware of.

Further, he says,

Here in India, there are several dangers. Of these, the two, Scylla and Charybdis, rank materialism and its opposite arrant superstition, must be avoided. There is the man today who after drinking the cup of Western wisdom, thinks that he knows everything. He laughs at the ancient sages. All Hindu thought to him is arrant trash — philosophy mere child’s prattle, and religion the superstition of fools. On the other hand, there is the man educated, but a sort of monomaniac, who runs to the other extreme and wants to explain the omen of this and that. He has philosophical and metaphysical, and Lord knows what other puerile explanations for every superstition that belongs to his peculiar race, or his peculiar gods, or his peculiar village. Every little village superstition is to him a mandate of the Vedas, and upon the carrying out of it, according to him, depends the national life. You must beware of this. I would rather see every one of you rank atheists than superstitious fools, for the atheist is alive and you can make something out of him. But if superstition enters, the brain is gone, the brain is softening, degradation has seized upon the life. Avoid these two. Brave, bold men, these are what we want. What we want is vigour in the blood, strength in the nerves, iron muscles and nerves of steel, not softening namby-pamby ideas. Avoid all these. Avoid all mystery. There is no mystery in religion.

Do the superstitions followed in Hinduism have the sanction of our Rishis and Sastras? No, he says

Vain delusion! Where indeed is that the case nowadays? Nowhere have I found the laws of the Rishis current in India, even when during my travels I searched carefully and thoroughly. The blind and not unoften meaningless customs sanctioned by the people, local prejudices and ideas, and the usages and ceremonials prevalent amongst women, are what really govern society everywhere! How many care to read the Shâstras or to lead society according to their ordinances after careful study?

To a question of Child marriage he says,

Amongst the educated classes in Bengal, the custom of marrying their boys too early is dying out gradually. The girls are also given in marriage a year or two older than before, but that has been under compulsion — from pecuniary want. Whatever might be the reason for it, the age of marrying girls should be raised still higher. But what will the poor father do? As soon as the girl grows up a little, every one of the female sex, beginning with the mother down to the relatives and neighbours even, will begin to cry out that he must find a bridegroom for her, and will not leave him in peace until he does so! And, about your religious hypocrites, the less said the better. In these days no one hears them, but still they will take up the role of leaders themselves. The rulers passed the Age of Consent Bill prohibiting a man under the threat of penalty to live with a girl of twelve years, and at once all these so-called leaders of your religion raised a tremendous hue and cry against it, sounding the alarm, “Alas, our religion is lost! As if religion consisted in making a girl a mother at the age of twelve or thirteen! So the rulers also naturally think, “Goodness gracious! What a religion is theirs! And these people lead political agitations and demand political rights!”

It is quite clear from his thoughts that certain practices in Hinduism need to go. These practices are not advised by our sages nor have the sanction of our Sastras.