Legal Question in Real Estate Law in Illinois

Is there a written lease? What does the lease say? If there is no written lease typically the tenant should be put on notice one way or the other -- usually that if no prior ok was given for the alterations then if they remove them at the end they are liable for damages and repairs necessitated by the removals. Otherwise the basic rule is that tenants are not allowed to make any alterations without prior consent and any additions become landlord's property, but claiming that today could result in a rebellion......