Tasha's has a section on replacing proficiencies granted by race in the section on customizing your origin and provides the example of swapping elven proficiency with a longbow for a tool proficiency. Does that mean you could swap all 4 weapon proficiencies from Elven Weapon Training for any 4 weapons or 4 tool proficiencies instead?
The only limit is the DM's approval
The optional rule from Tasha's states:
You can replace each of those proficiencies with a different one of your choice, following the restrictions on the Proficiency Swaps table.
The is no limit imposed except that the rule itself is an optional rule (as stated at the start of the Character Options section) and therefore the DM may impose a limit to the number of swaps a player/character can make.