the Valheim Wiki states that army raids can be disabled by killing next biome boss.
so for trolls etc its killing The Elder.
the random raids however wont be disabled; so if youve killed The Elder you should have disabled "the forest is moving" base raid
you can however still get "the ground is shaking" which will be trolls attacking but is a random event that is triggered by you being close to your base (or a base; which is campfire, bed and workbench)