Is repentance permissible for one who has taken the belongings of others without their permission, if he intends to return them or their equivalent in secret, without informing them of what he has done?

Among the conditions for the acceptance of repentance is the restoration of rights to their owners. Therefore, you must return the money you took to them. This can be done either directly, requesting forgiveness if possible, or indirectly if informing them would cause you harm, in which case you are absolved without informing them.