The Chesterfield School Board last night unanimously approved delaying several key measures and eliminating others in its six-year strategic plan because of budget constraints. “For the next several years, we’re going to be in a mode of keeping what we have,“ School Board Chairman Marshall Trammell Jr. said in an interview. He was not at last night’s meeting. “Some of those things that we deem necessary, we don’t see the money for in the horizon any time soon.“