The most well known banishing ritual is the Golden Dawn’s Lesser Banishing Ritual of the Pentagram, abbreviated as the LBRP. If you search Google, you can easily find instructions on how to do it. It clears the area using Divine Names, sets a boundary and invokes the power of four archangels at the cardinal points to enforce it.
You can also try this one:
If you are truly under a curse, a daily banishing ritual will help you. it will give you breathing space so you can bring your will to bear on breaking whatever force was sent against you.