Can doublestrike kill a creature with totem armor?
Yes, a creature with doublestrike can kill a creature with totem armor in combat.
In a combat phase that involves first/double strike creatures, there is an additional combat damage step. In the first, only creatures with first/double strike deal damage, so the 3/4 deals 3 damage to the 3/3. Players then get a round of priority, which means state-based actions are checked and the 3/3 that received lethal damage dies. Totem armor replaces that death and, unlike with regeneration, the 3/3 remains in combat. In the next damage step, the 3/3 and the 3/4 deal damage to each other and the 3/3 creature dies for good.


Combat Damage Step

510.1. First, the active player announces how each attacking creature assigns its combat damage, then the defending player announces how each blocking creature assigns its combat damage.
510.2. Second, all combat damage that’s been assigned is dealt simultaneously.
510.3. Third, the active player gets priority.
510.4. If at least one attacking or blocking creature has first strike (see rule 702.7) or double strike (see rule 702.4) as the combat damage step begins, the only creatures that assign combat damage in that step are those with first strike or double strike. After that step, instead of proceeding to the end of combat step, the phase gets a second combat damage step.
704.3. Whenever a player would get priority (see rule 116, “Timing and Priority”), the game checks for any of the listed conditions for state-based actions, then performs all applicable state-based actions simultaneously as a single event.