How to use cancel order?

[19Patrick99]

Hello,
I'm tryng to write my first strategy and i have problems regard cancel order.
With first trigger there will create 3, buy market and two sell order (TP and SL)
with the second trigger (crossover close on relative_max) i would to cancel them and update them with new level.

"import backtrader as bt
from backtrader import CommInfoBase

if name == 'main':

class RippleBoing(bt.Strategy):
    params = (
        ('minimum_bars', 4),
        ('offset_TP', 2),
        ('offset_SL', 1),
        ('Lenght_BB', 20),
    )

    def __init__(self):
        self.bollinger = bt.indicators.BollingerBands(period=self.params.Lenght_BB, devfactor=2)
        self.fascia_inferiore = self.bollinger.bot
        self.counter = 0

        # condizioni
        self.Crossunder = bt.ind.CrossDown(self.datas[0].close, self.fascia_inferiore)

    def next(self):
        if self.datas[0].close[0] < self.datas[0].open[0]:
            self.counter += 1
        else:
            self.counter = 0

        if self.Crossunder and self.counter >= self.params.minimum_bars:
            relative_max = self.datas[0].high[-self.counter]
            excursion = round((relative_max - self.datas[0].close), 5)
            stop_loss = round((self.datas[0].close - (excursion * self.params.offset_SL)), 5)
            take_profit = round((self.datas[0].close + (excursion * self.params.offset_TP)), 5)
            self.buy(exectype=bt.Order.Market)
            tp = ordine_tp = self.sell(exectype=bt.Order.Limit, price=take_profit)
            sl = ordine_sl = self.sell(exectype=bt.Order.Stop, price=stop_loss)

        if bt.ind.CrossUp(self.datas[0].close[0], relative_max):
            self.broker.cancel(tp)
            self.broker.cancel(sl)

returns:
UnboundLocalError: local variable 'relative_max' referenced before assignment

what i'm doing wrong?

Thank!!