Please add mechanism to remove unwanted/spam "Team Up"

Hi,

Suggestion :
Please add mechanism to drop unused/unwanted TU abilities for reasons below :
1. Very limited space (13),considering 1 char could have 15 TU : 3 skill x 5 level per skill
2. Some particular TU is so expensive and hard to used in normal gameplay, i.e: control shift 17, ballistic silvo 20, sniper rifle 17, sentinel of liberty 18
3. Currently it's possible to have multiple TU, i.e : 13 TU of ballistic silvo lvl 5.

It's like a spam when u have 13 TU of "ballistic silvo" while u need more space for other TU.

Thx.