Lyase that catalyzes the C1-decarboxylation of 4-hydroxy-3- methoxy-5-(all-trans-decaprenyl)benzoic acid into 2-methoxy-6-(all- trans-decaprenyl)phenol during ubiquinone biosynthesis. {ECO:0000255|HAMAP-Rule:MF_03111, ECO:0000269|PubMed:38295803, ECO:0000269|PubMed:38425362}. This is the function of Ensembl gene identifier ENSG00000167113 (COQ4, coenzyme Q4).