The can in that statement is merely indicating the possibility that the d20 will roll 1 and thus activate a Wild Magic Surge, there is NO option to avoid rolling.
The Tides of Chaos almost guarantees there will eventually be a Wild Magic Surge, but it's totally at the whim of the GM. After all, if the GM is tired of them, he won't activate one at all, and your next Long Rest will negate the imminent Wild Magic Surge. (That's why it's only an 'almost guarantees'.)
When you are a Wild Mage and cast a spell higher than 1st, you roll the die, you don't get a choice, and that's part the price you have to pay to be a Wild Mage.
Although it's true that people house rule all kinds of things, just make bloody sure you make all house rules clear to all players, and go out of your way to point out ones that are specific to a class before someone takes that kind of character. (In this case, anyone thinking of a Wild Mage if you decide to alter the rules regarding it.)
The Tides of Chaos almost guarantees there will eventually be a Wild Magic Surge, but it's totally at the whim of the GM. After all, if the GM is tired of them, he won't activate one at all, and your next Long Rest will negate the imminent Wild Magic Surge. (That's why it's only an 'almost guarantees'.)
When you are a Wild Mage and cast a spell higher than 1st, you roll the die, you don't get a choice, and that's part the price you have to pay to be a Wild Mage.
Although it's true that people house rule all kinds of things, just make bloody sure you make all house rules clear to all players, and go out of your way to point out ones that are specific to a class before someone takes that kind of character. (In this case, anyone thinking of a Wild Mage if you decide to alter the rules regarding it.)
