It is as easy for her to just stop her OCD rituals as it would be for you to just stop yourself from jumping out of the way of a car that is coming toward you at 50 miles per hour.
When she is doing a ritual, it is a fear response to an obsessive thought, impulse, or image.
So she may think that she needs to straighten out everything in her house and put all items at 90 degree angles on all tables because of a fear that if she did not, something horrible would happen to her family.
How those items and her family’s safety are related is not as important as her belief that she has to do her rituals or she will be responsible for some horrible fate befalling her family.
Therefore, stopping the ritual, to her, would ensure that something bad would happen to her family, and she is not willing to take that risk.
That is why she cannot just stop doing the ritual, what seems annoying and illogical to you seems absolutely necessary to her.