Temporarily deactivating while retaining resources

If you mean that the account would be retained and later reactivated without incurring costs for the time it was deactivated, then no, that's not possible.

The best you could do easily and at low risk is to scale down your resources, such as switching RDS databases to the smallest instance types, powering off EC2 instances, switching large EBS volumes to the cheapest applicable volume type (like sc1 for volumes >=200 GB), and so on.

A more convoluted approach would be to back up your resources, delete the active systems, and to rebuild your environment from the backups when you need it again, but without tested recovery plans, it's also an easy way to lose the environment completely and be left with a lessons-learnt slide about how the backups should've been made.