Flaxseeds play in important role in many keto recipes, so you usually can’t take them out unless you replace them with something.
For baked goods: Use one teaspoon of ground chia seeds for every tablespoon of ground flaxseeds. Allowing the ground chia seeds to sit in the batter for 15-20 minutes will help thicken it up.
For binding and thickening: Use about 1/4 cup of water mixed with 1 teaspoon of ground chia seeds or 1 1/2 tablespoons of whole chia seeds for every 1 tablespoon of ground flaxseeds.
For homemade energy bars or bites: Replace chia seeds measure-for-measure for flaxseeds.