Is IT Manager accountable for SLAs & OLAs?

Yes, Manager is responsible for SLA's

Yes IT Manager is responsible as technical aspects required to run the show is better known to him only.

A Service Level Agreement (SLA) is an agreement between an IT Service Provider and a Customer that is outside of IT. 

An SLA describes the service being delivered, documents service level targets and specifies the responsibilities of the IT Service Provider and the Customer. An SLA is based on customer requirements.  An SLA describes expectations of the Customer and a commitment by the Service Provider to meet those expectations. 

An Operating Level Agreement (OLA) is an agreement between an IT Service Provider and another part of the IT organization. 

OLAs often define supporting services (that is, services that are not directly used by the business but are required to deliver services) to be provided and the responsibilities of both parties. An OLA describes the service being delivered, documents service level targets and specifies the responsibilities of the IT Service Provider and the Service Recipient. An OLA describes expectations of the Service Recipient and a commitment by the Service Provider to meet those expectations.  OLAs can explain how services will be delivered to support SLAs. 

SLAs and OLAs should contain realistic service level targets that can be effectively achieved given the maturity of relevant ITSM processes.  Service targets should be compared to actual service performance and reported to the Customer.  SLAs and OLAs should contain provisions for service improvement in the event of service level “breaches.” 

A Service Level Manager should be defined for each service.  The Service Level Manager is responsible for working with Service Owners and the Customer for negotiating SLAs and OLAs (and any modifications to SLAs and OLAs).  Additionally, the Service Level Manager will analyze and report on service levels, ensure that service level targets are being met and will aid in resolving any disputes between the Customer and IT. 

For OLAs, the Service Level Manager may often be the same individual as the Service Owner.