Yes, or better yet, level 4. It's nice to have a level 6 trainer but you need to climb out of Division V in order to make money and retain your highest-paid players. You're paying $40K -- $50K per week more than I was paying for a trainer in USA Division IV, meaning you're losing out on about $600K worth of profit over the course of a season. Plus, the higher the level of the staff member, the more rapidly their salary increases, and unless you're prepared to pay an outrageous signing fee (again, since you must have done it once to get this guy in the first place) you're not going to be able to replace your trainer. If you do replace him, it'll only be by spending gobs of cash that could buy you better players or a bigger arena instead.
You can't train that many players effectively and training takes a long, long time. Teams in lower divisions are much better served by focusing on spending money on talent and arena expansion, not staff. Staff can wait until you have talent at every position and have an opportunity to train a NT-quality player.