You can not entirely opt out of any of the ETFs in Acorns' portfolios, nor of the stocks or bonds of which the ETFs are comprised. You also do not have the option of choosing to invest in any other stocks, bonds, Bitcoin, or other securities through Acorns.
Your Acorns account is a Limited Trading Authority account. You choose one of 5 Acorns investment portfolios, but Acorns decides the ETFs that make up those portfolios. Each portfolio uses different allocations of a variety of 4-6 different ETFs, according to its associated level of risk.
For more on Limited Trading Authority, please see our Customer Agreement [program-agreement] under section A3. Limited Trading Authority to Modify and Track Portfolios.